| Message ID | 1281595974-32279-3-git-send-email-haavard.skinnemoen@atmel.com |
|---|---|
| State | Accepted |
| Commit | 9cec2fc209a000655af77256a39ede7c7d441e56 |
| Delegated to: | Reinhard Meyer |
| Headers | show |
Hi Haavard, > The paging system which is required to set up caching properties has not > yet been initialized when the SDRAM is initialized. So when the > map_physmem() function is converted to return the physical address > unchanged, the SDRAM initialization will break on some boards. > > The avr32-specific uncached() macro will return an address which will > always cause uncached accessed to be made. Since this happens in the > board code, using avr32-specific features should be ok, and will allow > the SDRAM initialization to keep working. > > Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com> > --- > board/atmel/atngw100/atngw100.c | 4 +--- > board/atmel/atstk1000/atstk1000.c | 4 +--- > board/earthlcd/favr-32-ezkit/favr-32-ezkit.c | 4 +--- > board/mimc/mimc200/mimc200.c | 4 +--- > board/miromico/hammerhead/hammerhead.c | 4 +--- > 5 files changed, 5 insertions(+), 15 deletions(-) > > diff --git a/board/atmel/atngw100/atngw100.c b/board/atmel/atngw100/atngw100.c > index 004d8da..4580f55 100644 > --- a/board/atmel/atngw100/atngw100.c > +++ b/board/atmel/atngw100/atngw100.c > @@ -75,13 +75,11 @@ phys_size_t initdram(int board_type) > unsigned long actual_size; > void *sdram_base; > > - sdram_base = map_physmem(EBI_SDRAM_BASE, EBI_SDRAM_SIZE, MAP_NOCACHE); > + sdram_base = uncached(EBI_SDRAM_BASE); > > expected_size = sdram_init(sdram_base, &sdram_config); > actual_size = get_ram_size(sdram_base, expected_size); > > - unmap_physmem(sdram_base, EBI_SDRAM_SIZE); > - So this patch replaces a construct which seems to be valid over all architectures by a construct which is only used in avr32, right? It also deletes the explicit statement that such a mapping is not needed any further. Isn't this a step backward? Can't you put the functionality inside the map function and leave the unmap a noop? Cheers Detlev
Detlev Zundel <dzu@denx.de> wrote: > So this patch replaces a construct which seems to be valid over all > architectures by a construct which is only used in avr32, right? It > also deletes the explicit statement that such a mapping is not needed > any further. Problem is that in order to make the CFI driver work on avr32, we need to change the map_physmem() macro to return the physical address unchanged. > Isn't this a step backward? Can't you put the functionality inside the > map function and leave the unmap a noop? I agree it's a step backward, but since the previous flamewar didn't get us anywhere, I decided to go for a compromise this time. At least this small architecture-specific kludge is localized to architecture-specific code. The map_physmem() macro currently does exactly the same thing as the uncached() macro, and the unmap is a noop, but the next patch changes it in order to fix the CFI driver. If the next patch is applied without this patch being applied first, the SDRAM driver will do cached accesses during initialization, and that may cause the initialization to fail. Haavard
Hi Haavard, > Detlev Zundel <dzu@denx.de> wrote: >> So this patch replaces a construct which seems to be valid over all >> architectures by a construct which is only used in avr32, right? It >> also deletes the explicit statement that such a mapping is not needed >> any further. > > Problem is that in order to make the CFI driver work on avr32, we need > to change the map_physmem() macro to return the physical address > unchanged. I see. And I presume you cannot tell the situation apart inside map_physmem? >> Isn't this a step backward? Can't you put the functionality inside the >> map function and leave the unmap a noop? > > I agree it's a step backward, but since the previous flamewar didn't > get us anywhere, I decided to go for a compromise this time. At least > this small architecture-specific kludge is localized to > architecture-specific code. > > The map_physmem() macro currently does exactly the same thing as the > uncached() macro, and the unmap is a noop, but the next patch changes > it in order to fix the CFI driver. If the next patch is applied without > this patch being applied first, the SDRAM driver will do cached > accesses during initialization, and that may cause the initialization > to fail. Why not include a note to this extent into the git commit message? This would be a great help for other people to later understand why this change has been done the "backward way" that it was. Cheers Detlev
Detlev Zundel <dzu@denx.de> wrote: > > Problem is that in order to make the CFI driver work on avr32, we need > > to change the map_physmem() macro to return the physical address > > unchanged. > > I see. And I presume you cannot tell the situation apart inside > map_physmem? I don't think so. How do you propose we do that? > > The map_physmem() macro currently does exactly the same thing as the > > uncached() macro, and the unmap is a noop, but the next patch changes > > it in order to fix the CFI driver. If the next patch is applied without > > this patch being applied first, the SDRAM driver will do cached > > accesses during initialization, and that may cause the initialization > > to fail. > > Why not include a note to this extent into the git commit message? This > would be a great help for other people to later understand why this > change has been done the "backward way" that it was. The commit message already contains this: The paging system which is required to set up caching properties has not yet been initialized when the SDRAM is initialized. So when the map_physmem() function is converted to return the physical address unchanged, the SDRAM initialization will break on some boards. which is essentially the same thing, isn't it? Haavard
Hi Haavard, > Detlev Zundel <dzu@denx.de> wrote: >> > Problem is that in order to make the CFI driver work on avr32, we need >> > to change the map_physmem() macro to return the physical address >> > unchanged. >> >> I see. And I presume you cannot tell the situation apart inside >> map_physmem? > > I don't think so. How do you propose we do that? I don't know, that's why I'm asking. Let's take a step back and please excuse my ignorant question - why exactly does the CFI driver need the physical address unchanged? Isn't the real constraint that the address requested by CFI is uncached? Why can't this be done by map_physmem()? >> > The map_physmem() macro currently does exactly the same thing as the >> > uncached() macro, and the unmap is a noop, but the next patch changes >> > it in order to fix the CFI driver. If the next patch is applied without >> > this patch being applied first, the SDRAM driver will do cached >> > accesses during initialization, and that may cause the initialization >> > to fail. >> >> Why not include a note to this extent into the git commit message? This >> would be a great help for other people to later understand why this >> change has been done the "backward way" that it was. > > The commit message already contains this: > > The paging system which is required to set up caching properties has not > yet been initialized when the SDRAM is initialized. So when the > map_physmem() function is converted to return the physical address > unchanged, the SDRAM initialization will break on some boards. > > which is essentially the same thing, isn't it? For me this is not the same - it does not include a word why the change which you agree "looks backward" is something that we want to do. For me something like this would give me more information: Unfortunately we cannot make "map_physmem()/unmap_physmem()" on the AVR32 platform work with the CFI driver as it works on other platforms. [I don't understand why this is the case, so your explanation would go here ;) ] To still fix the issue we deliberately replace these generic routines by AVR32 specific routines. If someone can fix this using the generic patterns, patches are welcome. I believe that good docmumentation should include such pro- and con reasoning so that code changes can be comprehended even after the fact. Cheers Detlev
Dear Haavard Skinnemoen, Am 12.08.2010 08:52, schrieb Haavard Skinnemoen: > The paging system which is required to set up caching properties has not > yet been initialized when the SDRAM is initialized. So when the > map_physmem() function is converted to return the physical address > unchanged, the SDRAM initialization will break on some boards. > > The avr32-specific uncached() macro will return an address which will > always cause uncached accessed to be made. Since this happens in the > board code, using avr32-specific features should be ok, and will allow > the SDRAM initialization to keep working. > > Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com> Tested-by: Andreas Bießmann <biessmann@corscience.de> one colleague reported similar problems initialising SDRAM on our own board. I could not reproduce this issue here, however this patch fixed the problem. Thanks for that, it came the right time. This patch should be applied too. regards Andreas Bießmann
Haavard Skinnemoen schrieb: > The paging system which is required to set up caching properties has not > yet been initialized when the SDRAM is initialized. So when the > map_physmem() function is converted to return the physical address > unchanged, the SDRAM initialization will break on some boards. > > The avr32-specific uncached() macro will return an address which will > always cause uncached accessed to be made. Since this happens in the > board code, using avr32-specific features should be ok, and will allow > the SDRAM initialization to keep working. > > Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com> > --- > board/atmel/atngw100/atngw100.c | 4 +--- > board/atmel/atstk1000/atstk1000.c | 4 +--- > board/earthlcd/favr-32-ezkit/favr-32-ezkit.c | 4 +--- > board/mimc/mimc200/mimc200.c | 4 +--- > board/miromico/hammerhead/hammerhead.c | 4 +--- > 5 files changed, 5 insertions(+), 15 deletions(-) Applied to u-boot-atmel/avr32 Thanks, Reinhard
diff --git a/board/atmel/atngw100/atngw100.c b/board/atmel/atngw100/atngw100.c index 004d8da..4580f55 100644 --- a/board/atmel/atngw100/atngw100.c +++ b/board/atmel/atngw100/atngw100.c @@ -75,13 +75,11 @@ phys_size_t initdram(int board_type) unsigned long actual_size; void *sdram_base; - sdram_base = map_physmem(EBI_SDRAM_BASE, EBI_SDRAM_SIZE, MAP_NOCACHE); + sdram_base = uncached(EBI_SDRAM_BASE); expected_size = sdram_init(sdram_base, &sdram_config); actual_size = get_ram_size(sdram_base, expected_size); - unmap_physmem(sdram_base, EBI_SDRAM_SIZE); - if (expected_size != actual_size) printf("Warning: Only %lu of %lu MiB SDRAM is working\n", actual_size >> 20, expected_size >> 20); diff --git a/board/atmel/atstk1000/atstk1000.c b/board/atmel/atstk1000/atstk1000.c index c36cb57..d91d594 100644 --- a/board/atmel/atstk1000/atstk1000.c +++ b/board/atmel/atstk1000/atstk1000.c @@ -97,13 +97,11 @@ phys_size_t initdram(int board_type) unsigned long actual_size; void *sdram_base; - sdram_base = map_physmem(EBI_SDRAM_BASE, EBI_SDRAM_SIZE, MAP_NOCACHE); + sdram_base = uncached(EBI_SDRAM_BASE); expected_size = sdram_init(sdram_base, &sdram_config); actual_size = get_ram_size(sdram_base, expected_size); - unmap_physmem(sdram_base, EBI_SDRAM_SIZE); - if (expected_size != actual_size) printf("Warning: Only %lu of %lu MiB SDRAM is working\n", actual_size >> 20, expected_size >> 20); diff --git a/board/earthlcd/favr-32-ezkit/favr-32-ezkit.c b/board/earthlcd/favr-32-ezkit/favr-32-ezkit.c index 8af680f..d2843c9 100644 --- a/board/earthlcd/favr-32-ezkit/favr-32-ezkit.c +++ b/board/earthlcd/favr-32-ezkit/favr-32-ezkit.c @@ -68,13 +68,11 @@ phys_size_t initdram(int board_type) unsigned long actual_size; void *sdram_base; - sdram_base = map_physmem(EBI_SDRAM_BASE, EBI_SDRAM_SIZE, MAP_NOCACHE); + sdram_base = uncached(EBI_SDRAM_BASE); expected_size = sdram_init(sdram_base, &sdram_config); actual_size = get_ram_size(sdram_base, expected_size); - unmap_physmem(sdram_base, EBI_SDRAM_SIZE); - if (expected_size != actual_size) printf("Warning: Only %lu of %lu MiB SDRAM is working\n", actual_size >> 20, expected_size >> 20); diff --git a/board/mimc/mimc200/mimc200.c b/board/mimc/mimc200/mimc200.c index cc0f137..9940669 100644 --- a/board/mimc/mimc200/mimc200.c +++ b/board/mimc/mimc200/mimc200.c @@ -153,13 +153,11 @@ phys_size_t initdram(int board_type) unsigned long actual_size; void *sdram_base; - sdram_base = map_physmem(EBI_SDRAM_BASE, EBI_SDRAM_SIZE, MAP_NOCACHE); + sdram_base = uncached(EBI_SDRAM_BASE); expected_size = sdram_init(sdram_base, &sdram_config); actual_size = get_ram_size(sdram_base, expected_size); - unmap_physmem(sdram_base, EBI_SDRAM_SIZE); - if (expected_size != actual_size) printf("Warning: Only %lu of %lu MiB SDRAM is working\n", actual_size >> 20, expected_size >> 20); diff --git a/board/miromico/hammerhead/hammerhead.c b/board/miromico/hammerhead/hammerhead.c index 8b3e22c..5ab999e 100644 --- a/board/miromico/hammerhead/hammerhead.c +++ b/board/miromico/hammerhead/hammerhead.c @@ -80,13 +80,11 @@ phys_size_t initdram(int board_type) unsigned long actual_size; void *sdram_base; - sdram_base = map_physmem(EBI_SDRAM_BASE, EBI_SDRAM_SIZE, MAP_NOCACHE); + sdram_base = uncached(EBI_SDRAM_BASE); expected_size = sdram_init(sdram_base, &sdram_config); actual_size = get_ram_size(sdram_base, expected_size); - unmap_physmem(sdram_base, EBI_SDRAM_SIZE); - if (expected_size != actual_size) printf("Warning: Only %lu of %lu MiB SDRAM is working\n", actual_size >> 20, expected_size >> 20);
The paging system which is required to set up caching properties has not yet been initialized when the SDRAM is initialized. So when the map_physmem() function is converted to return the physical address unchanged, the SDRAM initialization will break on some boards. The avr32-specific uncached() macro will return an address which will always cause uncached accessed to be made. Since this happens in the board code, using avr32-specific features should be ok, and will allow the SDRAM initialization to keep working. Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com> --- board/atmel/atngw100/atngw100.c | 4 +--- board/atmel/atstk1000/atstk1000.c | 4 +--- board/earthlcd/favr-32-ezkit/favr-32-ezkit.c | 4 +--- board/mimc/mimc200/mimc200.c | 4 +--- board/miromico/hammerhead/hammerhead.c | 4 +--- 5 files changed, 5 insertions(+), 15 deletions(-)