| Message ID | 20210203170245.31236-1-miquel.raynal@bootlin.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | spi: Fix the logic around the maximum speed | expand |
Hi Miquel, On Wed, Feb 3, 2021 at 2:06 PM Miquel Raynal <miquel.raynal@bootlin.com> wrote: > > Commit 9326e4f1e5dd ("spi: Limit the spi device max speed to controller's max speed") > rationaly introduced a new condition on which the device's maximum > speed would be set to the controller's one: if the device advertizes a > higher speed than the one supported by the controller. Already fixed: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6820e812dafb4258bc14692f686eec5bde6fba86
Hi Fabio, Fabio Estevam <festevam@gmail.com> wrote on Wed, 3 Feb 2021 14:10:15 -0300: > Hi Miquel, > > On Wed, Feb 3, 2021 at 2:06 PM Miquel Raynal <miquel.raynal@bootlin.com> wrote: > > > > Commit 9326e4f1e5dd ("spi: Limit the spi device max speed to controller's max speed") > > rationaly introduced a new condition on which the device's maximum > > speed would be set to the controller's one: if the device advertizes a > > higher speed than the one supported by the controller. > > Already fixed: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6820e812dafb4258bc14692f686eec5bde6fba86 Oh crap :') Indeed I wasn't based on the right -rc to get the fix. Thanks for the heads up! Miquèl
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 51d7c004fbab..f59bf5094adb 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -3378,8 +3378,9 @@ int spi_setup(struct spi_device *spi) if (status) return status; - if (!spi->max_speed_hz || - spi->max_speed_hz > spi->controller->max_speed_hz) + if (spi->controller->max_speed_hz && + (!spi->max_speed_hz || + spi->max_speed_hz > spi->controller->max_speed_hz)) spi->max_speed_hz = spi->controller->max_speed_hz; mutex_lock(&spi->controller->io_mutex);
Commit 9326e4f1e5dd ("spi: Limit the spi device max speed to controller's max speed") rationaly introduced a new condition on which the device's maximum speed would be set to the controller's one: if the device advertizes a higher speed than the one supported by the controller. However, it seems that the SPI core does not enforce controllers to always advertize a maximum speed value. Other similar conditions in the SPI core always check that the controller->max_speed_hz was set before doing anything else. Not doing this check here breaks SPI controller drivers which do not advertize a maximum speed: - the controller maximum speed is 0 - the child device max speed is set to an apparently coeherent value - in this case the child device maximum speed is set to 0 Either (1) all controller drivers should set max_speed_hz or (2) the child device maximum speed should not be updated in this particular situation. Perhaps there is a rationale for not enforcing (1), but in any case as a fix it is safer to use solution (2). Fixes: 9326e4f1e5dd ("spi: Limit the spi device max speed to controller's max speed") Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> --- drivers/spi/spi.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)