Messages in this thread | | | From | Xin Hao <> | Subject | Re: [PATCH v2 1/1] spi: Assume GPIO CS active high in ACPI case | Date | Wed, 12 May 2021 11:16:43 +0800 |
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在 2021/5/11 下午10:09, Andy Shevchenko 写道: > Currently GPIO CS handling, when descriptors are in use, doesn't > take into consideration that in ACPI case the default polarity > is Active High and can't be altered. Instead we have to use the > per-chip definition provided by SPISerialBus() resource. > > Fixes: 766c6b63aa04 ("spi: fix client driver breakages when using GPIO descriptors") > Cc: Liguang Zhang <zhangliguang@linux.alibaba.com> > Cc: Jay Fang <f.fangjian@huawei.com> > Cc: Sven Van Asbroeck <thesven73@gmail.com> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Tested-by: Xin Hao <xhao@linux.alibaba.com> > --- > v2: refactor to avoid ternary (Mark, Sven), dropped comment changes (Mark) > drivers/spi/spi.c | 22 ++++++++++++++++++---- > 1 file changed, 18 insertions(+), 4 deletions(-) > > diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c > index cd40421b8f55..36ee33514b40 100644 > --- a/drivers/spi/spi.c > +++ b/drivers/spi/spi.c > @@ -820,15 +820,29 @@ static void spi_set_cs(struct spi_device *spi, bool enable, bool force) > > if (spi->cs_gpiod || gpio_is_valid(spi->cs_gpio)) { > if (!(spi->mode & SPI_NO_CS)) { > - if (spi->cs_gpiod) > - /* polarity handled by gpiolib */ > - gpiod_set_value_cansleep(spi->cs_gpiod, activate); > - else > + if (spi->cs_gpiod) { > + /* > + * Historically ACPI has no means of the GPIO polarity and > + * thus the SPISerialBus() resource defines it on the per-chip > + * basis. In order to avoid a chain of negations, the GPIO > + * polarity is considered being Active High. Even for the cases > + * when _DSD() is involved (in the updated versions of ACPI) > + * the GPIO CS polarity must be defined Active High to avoid > + * ambiguity. That's why we use enable, that takes SPI_CS_HIGH > + * into account. > + */ > + if (has_acpi_companion(&spi->dev)) > + gpiod_set_value_cansleep(spi->cs_gpiod, !enable);
it worked and code changed minimally, before ACPI & OF keeps no same rules, this patch is ok!
> + else > + /* Polarity handled by GPIO library */ > + gpiod_set_value_cansleep(spi->cs_gpiod, activate); > + } else { > /* > * invert the enable line, as active low is > * default for SPI. > */ > gpio_set_value_cansleep(spi->cs_gpio, !enable); > + } > } > /* Some SPI masters need both GPIO CS & slave_select */ > if ((spi->controller->flags & SPI_MASTER_GPIO_SS) &&
-- Best Regards! Xin Hao
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