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Date: Thu, 15 Oct 2015 15:50:55 -0500 From: "Franklin S Cooper Jr." <fcooper@...com> To: Heiner Kallweit <hkallweit1@...il.com> CC: "Ivan T. Ivanov" <iivanov.xz@...il.com>, Jarkko Nikula <jarkko.nikula@...ux.intel.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>, Mark Brown <broonie@...nel.org>, Sekhar Nori <nsekhar@...com>, <ssantosh@...nel.org>, "Ivan T. Ivanov" <iivanov@...sol.com>, <m-karicheri2@...com>, Andy Shevchenko <andy.shevchenko@...il.com> Subject: Re: [RFC][PATCH] spi: Setup the master controller driver before setting the chipselect On 10/14/2015 06:45 AM, Heiner Kallweit wrote: > On Wed, Oct 14, 2015 at 1:08 PM, Andy Shevchenko > <andy.shevchenko@...il.com> wrote: >> +Cc: Jarkko to see from spi-pxa2xx prospective >> >> On Wed, Oct 14, 2015 at 12:47 PM, Ivan T. Ivanov <iivanov.xz@...il.com> wrote: >>> Adding Andy. >>> >>> >>>> On Oct 13, 2015, at 12:01 AM, Franklin S Cooper Jr <fcooper@...com> wrote: >>>> >>>> Some devices depend on the master controller driver setup function being >>>> called before calling any chipselect functions. >>>> >>>> Insure that this is done otherwise uninitialized structures may be >>>> accessed causing a kernel panic. >> As far as I understand my concern should be about spi-dw driver. >> >> So, I have just tested yesterday's linux-next with and without >> proposed patch. Works for me: >> Tested-by: Andy Shevchenko <andy.shevchenko@...il.com> >> >>>> Signed-off-by: Franklin S Cooper Jr <fcooper@...com> >>>> --- >>>> drivers/spi/spi.c | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c >>>> index 38006cc..9374d82 100644 >>>> --- a/drivers/spi/spi.c >>>> +++ b/drivers/spi/spi.c >>>> @@ -2053,11 +2053,11 @@ int spi_setup(struct spi_device *spi) >>>> if (!spi->max_speed_hz) >>>> spi->max_speed_hz = spi->master->max_speed_hz; >>>> >>>> - spi_set_cs(spi, false); >>>> - >>>> if (spi->master->setup) >>>> status = spi->master->setup(spi); >>>> >>>> + spi_set_cs(spi, false); >>>> + >>>> dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s%u bits/w, %u Hz max --> %d\n", >>>> (int) (spi->mode & (SPI_CPOL | SPI_CPHA)), >>>> (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "", >>>> -- >>>> 2.6.1 >>>> >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-spi" in >>>> the body of a message to majordomo@...r.kernel.org >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> >> -- >> With Best Regards, >> Andy Shevchenko >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-spi" in >> the body of a message to majordomo@...r.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > The recent change to the bitbang driver leads to the the set_cs hook > of spi_master being set > now for all drivers using the bitbang layer. This hook is called also > from spi_setup and therefore > one possible side effect is issues with bitbang drivers implementing > the chipselect hook of > spi_bitbang with a dependency on the master being set up before. > The proposed patch looks good to me. > There should be no impact on drivers not using bitbang. Thank all. Since nothing obvious seems wrong with this patch I will resend this patch without the RFC. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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