| Message ID | 20190324175002.28969-7-kernel@martin.sperl.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | spi: bcm2835aux: bug fixes and improvements | expand |
Hi Martin, Am 24.03.19 um 18:49 schrieb kernel@martin.sperl.org: > From: Martin Sperl <kernel@martin.sperl.org> > > From personal bad experience (even as the author of the original driver) > it shows that native-cs is "somewhat" supported by the spi bus driver > when using a buggy device tree. > > So make sure that the driver is warning in dmesg about this fact > that we are running in a not supported mode that may have surprizing > limitations. > > Signed-off-by: Martin Sperl <kernel@martin.sperl.org> > Fixes: 1ea29b39f4c812ece2f936065a0a3d6fe44a263e please use a proper fixes tag. > --- > drivers/spi/spi-bcm2835aux.c | 33 +++++++++++++++++++++++++++++++++ > 1 file changed, 33 insertions(+) > > diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c > index c8acde017b6a..6af07dec5fdc 100644 > --- a/drivers/spi/spi-bcm2835aux.c > +++ b/drivers/spi/spi-bcm2835aux.c > @@ -396,6 +396,38 @@ static void bcm2835aux_spi_handle_err(struct spi_master *master, > bcm2835aux_spi_reset_hw(bs); > } > > +static int bcm2835aux_spi_setup(struct spi_device *spi) > +{ > + int ret; > + > + if (spi->mode & SPI_NO_CS) > + return 0; > + /* sanity check for native cs */ > + if (!gpio_is_valid(spi->cs_gpio)) { > + /* for dt-backwards compatibility: only support native on CS0 > + * known things not supported with broken native CS: > + * * multiple chip-selects: cs0-cs2 are all > + * simultaniously asserted whenever there is a transfer > + * this even includes SPI_NO_CS > + * * SPI_CS_HIGH: cs are always asserted low > + * * cs_change: cs is deasserted after each spi_transfer > + * * cs_delay_usec: cs is always deasserted one SCK cycle > + * after the last transfer > + * probably more... > + */ > + if (spi->chip_select == 0) { > + dev_err(&spi->dev, > + "native CS is not supported but may work for some use-cases for cs = 0 - please define a valid value cs-gpios in DT for complete feature set\n"); > + return 0; These messages are rather too long, please keep it in the ~ 80 char limit (in source code and dmesg). Or make it two lines ... Since we return with 0, i prefer to use dev_warn instead of dev_err. Thanks > + } > + dev_err(&spi->dev, > + "native CS is not supported for cs > 0 - please define a valid value cs-gpios in DT to enable multiple cs\n"); > + return -EINVAL; > + } > + > + return 0; > +} > +
diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c index c8acde017b6a..6af07dec5fdc 100644 --- a/drivers/spi/spi-bcm2835aux.c +++ b/drivers/spi/spi-bcm2835aux.c @@ -396,6 +396,38 @@ static void bcm2835aux_spi_handle_err(struct spi_master *master, bcm2835aux_spi_reset_hw(bs); } +static int bcm2835aux_spi_setup(struct spi_device *spi) +{ + int ret; + + if (spi->mode & SPI_NO_CS) + return 0; + /* sanity check for native cs */ + if (!gpio_is_valid(spi->cs_gpio)) { + /* for dt-backwards compatibility: only support native on CS0 + * known things not supported with broken native CS: + * * multiple chip-selects: cs0-cs2 are all + * simultaniously asserted whenever there is a transfer + * this even includes SPI_NO_CS + * * SPI_CS_HIGH: cs are always asserted low + * * cs_change: cs is deasserted after each spi_transfer + * * cs_delay_usec: cs is always deasserted one SCK cycle + * after the last transfer + * probably more... + */ + if (spi->chip_select == 0) { + dev_err(&spi->dev, + "native CS is not supported but may work for some use-cases for cs = 0 - please define a valid value cs-gpios in DT for complete feature set\n"); + return 0; + } + dev_err(&spi->dev, + "native CS is not supported for cs > 0 - please define a valid value cs-gpios in DT to enable multiple cs\n"); + return -EINVAL; + } + + return 0; +} + static int bcm2835aux_spi_probe(struct platform_device *pdev) { struct spi_master *master; @@ -425,6 +457,7 @@ static int bcm2835aux_spi_probe(struct platform_device *pdev) * a spi_transfer */ master->num_chipselect = 1; + master->setup = bcm2835aux_spi_setup; master->transfer_one = bcm2835aux_spi_transfer_one; master->handle_err = bcm2835aux_spi_handle_err; master->prepare_message = bcm2835aux_spi_prepare_message;