| Message ID | 1409847105-27241-1-git-send-email-dinguyen@opensource.altera.com |
|---|---|
| State | New |
| Headers | show |
> Jaehoon Chung (1): > ARM: dts: socfpga: unuse the slot-node and deprecate the supports-highspeed for dw-mmc > This patch is a bad idea. It removes support for two mmc cards on a single controller -- configuration hardware supports and configuration that allows using u-SD card on mcvevk board. Pavel
On Thursday 04 September 2014 11:11:44 dinguyen@opensource.altera.com wrote: > Hi Arnd, Kevin and Olof, > > Please consider pulling in these patches for v3.18. 5 of the 6 patches are > DTS updates and the 1 patch is updating the MAINTAINERS entry with my new > email address. Pulled into next/dt. It would be nice if you could in the future separate the DT updates from the other changes more, even if that means sending a separate patch or pull request for something as trivial as the MAINTAINERS update. For some reason your pull request ended up in my spam folder, where I only found it today when looking for something else. I don't know why this happened, but you might want to watch out for this happening again, and ping us if a future pull request doesn't get merged within a couple of days. > > The following changes since commit 52addcf9d6669fa439387610bc65c92fa0980cef: > > Linux 3.17-rc2 (2014-08-25 15:36:20 -0700) > > are available in the git repository at: > > git://git.rocketboards.org/linux-socfpga-next.git tags/socfpga_update_for_v3.18 > > for you to fetch changes up to 75a41826e2c5dc1dc0fd5195fc29b031c97337af: > > arm: dts: Add Altera SDRAM EDAC bindings & devicetree entries. (2014-09-04 10:15:52 -0500) > > ---------------------------------------------------------------- > arm: dts: Add Altera SDRAM EDAC bindings & devicetree entries. > Please try to be a little more verbose with the changelog, as this is what ends up in the git history for the merge commit. Thanks, Arnd
On Tuesday 09 September 2014 16:17:56 Pavel Machek wrote: > > Jaehoon Chung (1): > > ARM: dts: socfpga: unuse the slot-node and deprecate the supports-highspeed for dw-mmc > > > > This patch is a bad idea. It removes support for two mmc cards on a > single controller -- configuration hardware supports and configuration > that allows using u-SD card on mcvevk board. > Your objection comes too late, and to the wrong patch, since the driver and all other users have already been changed. We had a long discussion about this when the issue first came up, and we could not find any example of dw-mmc actually being used in a scenario with one controller that has multiple devices attached. Apparently every user out there instead uses multiple controller instances instead. Are you sure that the socfpga implementation is an exception from this? Arnd
On 09/09/2014 09:55 AM, Arnd Bergmann wrote: > On Thursday 04 September 2014 11:11:44 dinguyen@opensource.altera.com wrote: >> Hi Arnd, Kevin and Olof, >> >> Please consider pulling in these patches for v3.18. 5 of the 6 patches are >> DTS updates and the 1 patch is updating the MAINTAINERS entry with my new >> email address. > > Pulled into next/dt. It would be nice if you could in the future > separate the DT updates from the other changes more, even if that means > sending a separate patch or pull request for something as trivial as > the MAINTAINERS update. Will keep this in mind in the future. > > For some reason your pull request ended up in my spam folder, where > I only found it today when looking for something else. I don't know > why this happened, but you might want to watch out for this happening > again, and ping us if a future pull request doesn't get merged within > a couple of days. > I was going to give it a week. >> >> The following changes since commit 52addcf9d6669fa439387610bc65c92fa0980cef: >> >> Linux 3.17-rc2 (2014-08-25 15:36:20 -0700) >> >> are available in the git repository at: >> >> git://git.rocketboards.org/linux-socfpga-next.git tags/socfpga_update_for_v3.18 >> >> for you to fetch changes up to 75a41826e2c5dc1dc0fd5195fc29b031c97337af: >> >> arm: dts: Add Altera SDRAM EDAC bindings & devicetree entries. (2014-09-04 10:15:52 -0500) >> >> ---------------------------------------------------------------- >> arm: dts: Add Altera SDRAM EDAC bindings & devicetree entries. >> > > Please try to be a little more verbose with the changelog, as this > is what ends up in the git history for the merge commit. > Will do... Thanks, Dinh
On Tue 2014-09-09 17:02:34, Arnd Bergmann wrote: > On Tuesday 09 September 2014 16:17:56 Pavel Machek wrote: > > > Jaehoon Chung (1): > > > ARM: dts: socfpga: unuse the slot-node and deprecate the supports-highspeed for dw-mmc > > > > > > > This patch is a bad idea. It removes support for two mmc cards on a > > single controller -- configuration hardware supports and configuration > > that allows using u-SD card on mcvevk board. > > > > Your objection comes too late, and to the wrong patch, since the > driver and all other users have already been changed. We had a long > discussion about this when the issue first came up, and we could > not find any example of dw-mmc actually being used in a scenario > with one controller that has multiple devices attached. Well, this is not first time I raised this. 3.17 is not yet out, so we still have chance to fix regressions without major fuss. > Apparently every user out there instead uses multiple controller > instances instead. Are you sure that the socfpga implementation > is an exception from this? Marek Vasut has the hardware. His board apprently has uSD and eMMC, and I believe it has just one controller. I'll try to get details. Pavel
On 9 September 2014 23:02, Pavel Machek <pavel@denx.de> wrote: > On Tue 2014-09-09 17:02:34, Arnd Bergmann wrote: >> On Tuesday 09 September 2014 16:17:56 Pavel Machek wrote: >> > > Jaehoon Chung (1): >> > > ARM: dts: socfpga: unuse the slot-node and deprecate the supports-highspeed for dw-mmc >> > > >> > >> > This patch is a bad idea. It removes support for two mmc cards on a >> > single controller -- configuration hardware supports and configuration >> > that allows using u-SD card on mcvevk board. >> > >> >> Your objection comes too late, and to the wrong patch, since the >> driver and all other users have already been changed. We had a long >> discussion about this when the issue first came up, and we could >> not find any example of dw-mmc actually being used in a scenario >> with one controller that has multiple devices attached. > > Well, this is not first time I raised this. 3.17 is not yet out, so we > still have chance to fix regressions without major fuss. > >> Apparently every user out there instead uses multiple controller >> instances instead. Are you sure that the socfpga implementation >> is an exception from this? > > Marek Vasut has the hardware. His board apprently has uSD and eMMC, > and I believe it has just one controller. I'll try to get details. > Just wanted to highlight some of the reasons to why the earlier discussion we have had, came to the conclusion to remove the slot node. 1) The mmc core don't support multiple cards attached to the same host, it never has. Also, I am not aware of any requests that suggested us to add it. Due to obvious reasons from performance perspective it's simply a really bad idea, that's likely also why there haven't been any requests for it. 2) On the host level, the support for handle multiple slots in DT for dw-mmc has been broken. While dw-mmc parsed the DT nodes for slots, it screwed up configurations. Thus the support for slots have never worked as expected from DT point of view. Kind regards Uffe
On Wed 2014-09-10 09:13:27, Ulf Hansson wrote: > On 9 September 2014 23:02, Pavel Machek <pavel@denx.de> wrote: > > On Tue 2014-09-09 17:02:34, Arnd Bergmann wrote: > >> On Tuesday 09 September 2014 16:17:56 Pavel Machek wrote: > >> > > Jaehoon Chung (1): > >> > > ARM: dts: socfpga: unuse the slot-node and deprecate the supports-highspeed for dw-mmc > >> > > > >> > > >> > This patch is a bad idea. It removes support for two mmc cards on a > >> > single controller -- configuration hardware supports and configuration > >> > that allows using u-SD card on mcvevk board. > >> > > >> > >> Your objection comes too late, and to the wrong patch, since the > >> driver and all other users have already been changed. We had a long > >> discussion about this when the issue first came up, and we could > >> not find any example of dw-mmc actually being used in a scenario > >> with one controller that has multiple devices attached. > > > > Well, this is not first time I raised this. 3.17 is not yet out, so we > > still have chance to fix regressions without major fuss. > > > >> Apparently every user out there instead uses multiple controller > >> instances instead. Are you sure that the socfpga implementation > >> is an exception from this? > > > > Marek Vasut has the hardware. His board apprently has uSD and eMMC, > > and I believe it has just one controller. I'll try to get details. > > > > Just wanted to highlight some of the reasons to why the earlier > discussion we have had, came to the conclusion to remove the slot > node. > > 1) The mmc core don't support multiple cards attached to the same > host, it never has. Also, I am not aware of any requests that > suggested us to add it. Due to obvious reasons from performance > perspective it's simply a really bad idea, that's likely also why > there haven't been any requests for it. Well, that's Linux problem, right? (And why is it bad idea, btw? The bandwidth will be shared between the controllers, ok, that does not sound too bad.) > 2) On the host level, the support for handle multiple slots in DT for > dw-mmc has been broken. While dw-mmc parsed the DT nodes for slots, it > screwed up configurations. Thus the support for slots have never > worked as expected from DT point of view. Well, DT is supposed to describe the hardware. From your description, it seems that linux does not support two slots on one controller and DT parsing code basically ignores the slots. (Logical, if it can't support two slots). So now we are breaking DT description due to Linux limitations. Which a) makes it hard for any other os not having same limitation b) makes it hard for people to fix the limitation c) does not really solve anything d) breaks backward compatibility with old dts If nothing, d) should be argument not to do this. Pavel
On 10 September 2014 10:33, Pavel Machek <pavel@denx.de> wrote: > On Wed 2014-09-10 09:13:27, Ulf Hansson wrote: >> On 9 September 2014 23:02, Pavel Machek <pavel@denx.de> wrote: >> > On Tue 2014-09-09 17:02:34, Arnd Bergmann wrote: >> >> On Tuesday 09 September 2014 16:17:56 Pavel Machek wrote: >> >> > > Jaehoon Chung (1): >> >> > > ARM: dts: socfpga: unuse the slot-node and deprecate the supports-highspeed for dw-mmc >> >> > > >> >> > >> >> > This patch is a bad idea. It removes support for two mmc cards on a >> >> > single controller -- configuration hardware supports and configuration >> >> > that allows using u-SD card on mcvevk board. >> >> > >> >> >> >> Your objection comes too late, and to the wrong patch, since the >> >> driver and all other users have already been changed. We had a long >> >> discussion about this when the issue first came up, and we could >> >> not find any example of dw-mmc actually being used in a scenario >> >> with one controller that has multiple devices attached. >> > >> > Well, this is not first time I raised this. 3.17 is not yet out, so we >> > still have chance to fix regressions without major fuss. >> > >> >> Apparently every user out there instead uses multiple controller >> >> instances instead. Are you sure that the socfpga implementation >> >> is an exception from this? >> > >> > Marek Vasut has the hardware. His board apprently has uSD and eMMC, >> > and I believe it has just one controller. I'll try to get details. >> > >> >> Just wanted to highlight some of the reasons to why the earlier >> discussion we have had, came to the conclusion to remove the slot >> node. >> >> 1) The mmc core don't support multiple cards attached to the same >> host, it never has. Also, I am not aware of any requests that >> suggested us to add it. Due to obvious reasons from performance >> perspective it's simply a really bad idea, that's likely also why >> there haven't been any requests for it. > > Well, that's Linux problem, right? (And why is it bad idea, btw? The > bandwidth will be shared between the controllers, ok, that does not > sound too bad.) Bandwidth is just one issue. Latency is yet another, which is probably far worse to handle than bandwidth. > >> 2) On the host level, the support for handle multiple slots in DT for >> dw-mmc has been broken. While dw-mmc parsed the DT nodes for slots, it >> screwed up configurations. Thus the support for slots have never >> worked as expected from DT point of view. > > Well, DT is supposed to describe the hardware. From your description, > it seems that linux does not support two slots on one controller and > DT parsing code basically ignores the slots. (Logical, if it can't > support two slots). > > So now we are breaking DT description due to Linux limitations. Which > > a) makes it hard for any other os not having same limitation > > b) makes it hard for people to fix the limitation > > c) does not really solve anything Yes it does, the problem in 2) gets fixed. > > d) breaks backward compatibility with old dts According to 2), it has never worked - so we don't break anything. > > If nothing, d) should be argument not to do this. > Pavel > -- > (english) http://www.livejournal.com/~pavelmachek > (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html Kind regards Uffe
Hi! > >> 2) On the host level, the support for handle multiple slots in DT for > >> dw-mmc has been broken. While dw-mmc parsed the DT nodes for slots, it > >> screwed up configurations. Thus the support for slots have never > >> worked as expected from DT point of view. > > > > Well, DT is supposed to describe the hardware. From your description, > > it seems that linux does not support two slots on one controller and > > DT parsing code basically ignores the slots. (Logical, if it can't > > support two slots). > > > > So now we are breaking DT description due to Linux limitations. Which > > > > a) makes it hard for any other os not having same limitation > > > > b) makes it hard for people to fix the limitation > > > > c) does not really solve anything > > Yes it does, the problem in 2) gets fixed. > > > > > d) breaks backward compatibility with old dts > > According to 2), it has never worked - so we don't break anything. Umm? u-SD worked for me in 3.14, 3.15 and 3.16 with the device tree, and with single-slot described in the device tree. Now I have to change dtb-s to keep working configuration, which is something device tree should never ever do. Is it so hard to just fix the multiple slot parsing? Pavel
On 9/10/14, 6:00 AM, Pavel Machek wrote: > Hi! > >>>> 2) On the host level, the support for handle multiple slots in DT for >>>> dw-mmc has been broken. While dw-mmc parsed the DT nodes for slots, it >>>> screwed up configurations. Thus the support for slots have never >>>> worked as expected from DT point of view. >>> >>> Well, DT is supposed to describe the hardware. From your description, >>> it seems that linux does not support two slots on one controller and >>> DT parsing code basically ignores the slots. (Logical, if it can't >>> support two slots). >>> >>> So now we are breaking DT description due to Linux limitations. Which >>> >>> a) makes it hard for any other os not having same limitation >>> >>> b) makes it hard for people to fix the limitation >>> >>> c) does not really solve anything >> >> Yes it does, the problem in 2) gets fixed. >> >>> >>> d) breaks backward compatibility with old dts >> >> According to 2), it has never worked - so we don't break anything. > > Umm? u-SD worked for me in 3.14, 3.15 and 3.16 with the device tree, > and with single-slot described in the device tree. Now I have to > change dtb-s to keep working configuration, which is something device > tree should never ever do. I tested the DTB with and without the patch, and it all works fine. Dinh > > Is it so hard to just fix the multiple slot parsing? > > Pavel >
On Tuesday, September 09, 2014 at 11:02:32 PM, Pavel Machek wrote: > On Tue 2014-09-09 17:02:34, Arnd Bergmann wrote: > > On Tuesday 09 September 2014 16:17:56 Pavel Machek wrote: > > > > Jaehoon Chung (1): > > > > ARM: dts: socfpga: unuse the slot-node and deprecate the > > > > supports-highspeed for dw-mmc > > > > > > This patch is a bad idea. It removes support for two mmc cards on a > > > single controller -- configuration hardware supports and configuration > > > that allows using u-SD card on mcvevk board. This is not true, the MCVEVK does _NOT_ have two cards on a single controller. > > Your objection comes too late, and to the wrong patch, since the > > driver and all other users have already been changed. We had a long > > discussion about this when the issue first came up, and we could > > not find any example of dw-mmc actually being used in a scenario > > with one controller that has multiple devices attached. > > Well, this is not first time I raised this. 3.17 is not yet out, so we > still have chance to fix regressions without major fuss. > > > Apparently every user out there instead uses multiple controller > > instances instead. Are you sure that the socfpga implementation > > is an exception from this? > > Marek Vasut has the hardware. His board apprently has uSD and eMMC, > and I believe it has just one controller. I'll try to get details. So please go ahead with this PR, sorry for blocking it. Best regards, Marek Vasut
Hi Arnd, Kevin and Olof, Please consider pulling in these patches for v3.18. 5 of the 6 patches are DTS updates and the 1 patch is updating the MAINTAINERS entry with my new email address. Thanks, Dinh The following changes since commit 52addcf9d6669fa439387610bc65c92fa0980cef: Linux 3.17-rc2 (2014-08-25 15:36:20 -0700) are available in the git repository at: git://git.rocketboards.org/linux-socfpga-next.git tags/socfpga_update_for_v3.18 for you to fetch changes up to 75a41826e2c5dc1dc0fd5195fc29b031c97337af: arm: dts: Add Altera SDRAM EDAC bindings & devicetree entries. (2014-09-04 10:15:52 -0500) ---------------------------------------------------------------- arm: dts: Add Altera SDRAM EDAC bindings & devicetree entries. ---------------------------------------------------------------- Dinh Nguyen (4): MAINTAINERS: update entries for ARM/SOCFPGA platform ARM: dts: socfpga: remove extra alias in the ArriaV devkit ARM: dts: socfpga: Add SD card detect ARM: dts: socfpga: memreserve first 4KB for future system use Jaehoon Chung (1): ARM: dts: socfpga: unuse the slot-node and deprecate the supports-highspeed for dw-mmc Thor Thayer (1): arm: dts: Add Altera SDRAM EDAC bindings & devicetree entries. .../devicetree/bindings/arm/altera/socfpga-sdram-edac.txt | 15 +++++++++++++++ MAINTAINERS | 7 +++++-- arch/arm/boot/dts/socfpga.dtsi | 11 +++++++++++ arch/arm/boot/dts/socfpga_arria5.dtsi | 11 +++++------ arch/arm/boot/dts/socfpga_arria5_socdk.dts | 7 ------- arch/arm/boot/dts/socfpga_cyclone5.dtsi | 13 ++++++------- arch/arm/boot/dts/socfpga_cyclone5_socdk.dts | 4 ++++ arch/arm/boot/dts/socfpga_vt.dts | 9 +++------ 8 files changed, 49 insertions(+), 28 deletions(-) create mode 100644 Documentation/devicetree/bindings/arm/altera/socfpga-sdram-edac.txt