| Message ID | 20181114063703.13379-1-ms@dev.tdt.de |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | [v2] net: phy: mdio-gpio: fix access that may sleep | expand |
On Wed, Nov 14, 2018 at 07:37:03AM +0100, Martin Schiller wrote: > This commit re-enables support for slow GPIO pins. It was initially > introduced by commit > 2d6c9091ab7630dfcf34417c6683ce4764d7d40a > and got lost by commit > 7e5fbd1e0700f1bdb94508f84ec2aeb01eed7b12 Hi Martin Was it really lost? It looks like _cansleep() just adds an extra check might_sleep_if(extra_checks), but it does not change any functionality. So the change itself is O.K, i'm just not too sure about the commit message. Andrew
On 2018-11-14 08:05, Andrew Lunn wrote: > On Wed, Nov 14, 2018 at 07:37:03AM +0100, Martin Schiller wrote: >> This commit re-enables support for slow GPIO pins. It was initially >> introduced by commit >> 2d6c9091ab7630dfcf34417c6683ce4764d7d40a >> and got lost by commit >> 7e5fbd1e0700f1bdb94508f84ec2aeb01eed7b12 > > Hi Martin > > Was it really lost? It looks like _cansleep() just adds an extra check > might_sleep_if(extra_checks), but it does not change any > functionality. Well, you are right, the functionality itself is not broken, but using the NON _cansleep() functions on GPIOs that have the cansleep flag set, this leads to a lot of kernel warnings/backtraces which makes the system in fact useless. Thats the WARN_ON() here: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpio/gpiolib.c?h=v4.20-rc2#n2992 and here: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpio/gpiolib.c?h=v4.20-rc2#n3304 > > So the change itself is O.K, i'm just not too sure about the commit > message. > > Andrew Hmm, ok. What would you suggest for a better commit message? I thought it would be helpful to know that this was already in there and got (inadvertently?) removed by another commit. Martin
Hello! On 14.11.2018 9:37, Martin Schiller wrote: > This commit re-enables support for slow GPIO pins. It was initially > introduced by commit > 2d6c9091ab7630dfcf34417c6683ce4764d7d40a > and got lost by commit > 7e5fbd1e0700f1bdb94508f84ec2aeb01eed7b12 This is not how you cite a commit: 12 digits is enough and they should be followed by the commit summary enclosed in (""). > > Also add a warning about slow GPIO pins like it is done in i2c-gpio. > > Signed-off-by: Martin Schiller <ms@dev.tdt.de> > --- > v2: > - fixed copy/paste bug in warning about slow GPIO pins > --- > drivers/net/phy/mdio-gpio.c | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/drivers/net/phy/mdio-gpio.c b/drivers/net/phy/mdio-gpio.c > index 33265747bf39..6c1cca14689b 100644 > --- a/drivers/net/phy/mdio-gpio.c > +++ b/drivers/net/phy/mdio-gpio.c [...] > @@ -162,6 +162,11 @@ static int mdio_gpio_probe(struct platform_device *pdev) > if (ret) > return ret; > > + if (gpiod_cansleep(bitbang->mdc) || gpiod_cansleep(bitbang->mdio) > + || gpiod_cansleep(bitbang->mdo)) The line continued that way blends with the branch below, the networking code uses a different style of line continuation where the continuation line starts immediately below the 1st gpiod_cansleep() call. Also, || should be left on the 1st line... > + dev_warn(&pdev->dev, "Slow GPIO pins might wreak havoc into" > + "MDIO bus timing"); > + > if (pdev->dev.of_node) { > bus_id = of_alias_get_id(pdev->dev.of_node, "mdio-gpio"); > if (bus_id < 0) { MBR, Sergei
On Wed, Nov 14, 2018 at 08:43:49AM +0100, Martin Schiller wrote: > On 2018-11-14 08:05, Andrew Lunn wrote: > >On Wed, Nov 14, 2018 at 07:37:03AM +0100, Martin Schiller wrote: > >>This commit re-enables support for slow GPIO pins. It was initially > >>introduced by commit > >> 2d6c9091ab7630dfcf34417c6683ce4764d7d40a > >>and got lost by commit > >> 7e5fbd1e0700f1bdb94508f84ec2aeb01eed7b12 > > > >Hi Martin > > > >Was it really lost? It looks like _cansleep() just adds an extra check > >might_sleep_if(extra_checks), but it does not change any > >functionality. > > Well, you are right, the functionality itself is not broken, but using > the NON _cansleep() functions on GPIOs that have the cansleep flag set, > this leads to a lot of kernel warnings/backtraces which makes the system > in fact useless. > > Thats the WARN_ON() here: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpio/gpiolib.c?h=v4.20-rc2#n2992 > > and here: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpio/gpiolib.c?h=v4.20-rc2#n3304 Hi Martin Right, this is really what you are fixing. So the commit message should talk about these WARN_ON being hit. > > > >So the change itself is O.K, i'm just not too sure about the commit > >message. > > > > Andrew > > Hmm, ok. What would you suggest for a better commit message? Up until commit XXX, the _cansleep variants of the gpio_ API was used. After that commit and the change to gpiod_ API, the _cansleep() was dropped. This then results in WARN_ON() when used with GPIO devices which do sleep. Add back the _cansleep() to avoid this. This is something which is useful in stable. So please base this fix on DaveM net tree, not net-next, and include a Fixes: tag for the patch which broke it. Thanks Andrew
From: Martin Schiller <ms@dev.tdt.de> Date: Wed, 14 Nov 2018 07:37:03 +0100 > @@ -162,6 +162,11 @@ static int mdio_gpio_probe(struct platform_device *pdev) > if (ret) > return ret; > > + if (gpiod_cansleep(bitbang->mdc) || gpiod_cansleep(bitbang->mdio) > + || gpiod_cansleep(bitbang->mdo)) Please fix the formatting here, operators like "||" and "&&" never begin a line, they must always finish a line.
diff --git a/drivers/net/phy/mdio-gpio.c b/drivers/net/phy/mdio-gpio.c index 33265747bf39..6c1cca14689b 100644 --- a/drivers/net/phy/mdio-gpio.c +++ b/drivers/net/phy/mdio-gpio.c @@ -63,7 +63,7 @@ static void mdio_dir(struct mdiobb_ctrl *ctrl, int dir) * assume the pin serves as pull-up. If direction is * output, the default value is high. */ - gpiod_set_value(bitbang->mdo, 1); + gpiod_set_value_cansleep(bitbang->mdo, 1); return; } @@ -78,7 +78,7 @@ static int mdio_get(struct mdiobb_ctrl *ctrl) struct mdio_gpio_info *bitbang = container_of(ctrl, struct mdio_gpio_info, ctrl); - return gpiod_get_value(bitbang->mdio); + return gpiod_get_value_cansleep(bitbang->mdio); } static void mdio_set(struct mdiobb_ctrl *ctrl, int what) @@ -87,9 +87,9 @@ static void mdio_set(struct mdiobb_ctrl *ctrl, int what) container_of(ctrl, struct mdio_gpio_info, ctrl); if (bitbang->mdo) - gpiod_set_value(bitbang->mdo, what); + gpiod_set_value_cansleep(bitbang->mdo, what); else - gpiod_set_value(bitbang->mdio, what); + gpiod_set_value_cansleep(bitbang->mdio, what); } static void mdc_set(struct mdiobb_ctrl *ctrl, int what) @@ -97,7 +97,7 @@ static void mdc_set(struct mdiobb_ctrl *ctrl, int what) struct mdio_gpio_info *bitbang = container_of(ctrl, struct mdio_gpio_info, ctrl); - gpiod_set_value(bitbang->mdc, what); + gpiod_set_value_cansleep(bitbang->mdc, what); } static const struct mdiobb_ops mdio_gpio_ops = { @@ -162,6 +162,11 @@ static int mdio_gpio_probe(struct platform_device *pdev) if (ret) return ret; + if (gpiod_cansleep(bitbang->mdc) || gpiod_cansleep(bitbang->mdio) + || gpiod_cansleep(bitbang->mdo)) + dev_warn(&pdev->dev, "Slow GPIO pins might wreak havoc into" + "MDIO bus timing"); + if (pdev->dev.of_node) { bus_id = of_alias_get_id(pdev->dev.of_node, "mdio-gpio"); if (bus_id < 0) {
This commit re-enables support for slow GPIO pins. It was initially introduced by commit 2d6c9091ab7630dfcf34417c6683ce4764d7d40a and got lost by commit 7e5fbd1e0700f1bdb94508f84ec2aeb01eed7b12 Also add a warning about slow GPIO pins like it is done in i2c-gpio. Signed-off-by: Martin Schiller <ms@dev.tdt.de> --- v2: - fixed copy/paste bug in warning about slow GPIO pins --- drivers/net/phy/mdio-gpio.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)