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SubjectRe: [PATCH v2 4/4] spi: spi-davinci: Add support for SPI_CS_WORD
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On 09/13/2018 08:44 AM, Geert Uytterhoeven wrote:
> Hi David,
>
> On Thu, Sep 13, 2018 at 2:40 AM David Lechner <david@lechnology.com> wrote:
>> This adds support for the SPI_CS_WORD flag to the TI DaVinci SPI
>> driver. This mode can be used as long as we are using the hardware
>> chip select and not a GPIO chip select.
>>
>> Signed-off-by: David Lechner <david@lechnology.com>
>> ---
>> drivers/spi/spi-davinci.c | 11 ++++++++---
>> 1 file changed, 8 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c
>> index d502cf504deb..8f7dcbc53c57 100644
>> --- a/drivers/spi/spi-davinci.c
>> +++ b/drivers/spi/spi-davinci.c
>> @@ -230,7 +230,8 @@ static void davinci_spi_chipselect(struct spi_device *spi, int value)
>> !(spi->mode & SPI_CS_HIGH));
>> } else {
>> if (value == BITBANG_CS_ACTIVE) {
>> - spidat1 |= SPIDAT1_CSHOLD_MASK;
>> + if (!(spi->mode & SPI_CS_WORD))
>> + spidat1 |= SPIDAT1_CSHOLD_MASK;
>> spidat1 &= ~(0x1 << chip_sel);
>> }
>> }
>> @@ -440,8 +441,12 @@ static int davinci_spi_setup(struct spi_device *spi)
>> return retval;
>> }
>>
>> - if (internal_cs)
>> + if (internal_cs) {
>> set_io_bits(dspi->base + SPIPC0, 1 << spi->chip_select);
>> + } else if (spi->mode & SPI_CS_WORD) {
>> + dev_err(&spi->dev, "SPI_CS_WORD can't be use with GPIO CS\n");
>> + return -EINVAL;
>
> Does the SPI core fall back to splitting the transfer in this case?

Hmm... it doesn't look like it.

I suppose it might be best to modify the SPI core to say:

if ((spi->mode & SPI_CS_WORD) && (!(ctlr->mode_bits & SPI_CS_WORD) ||
gpio_is_valid(spi->cs_gpio)) {

instead of:

if ((spi->mode & SPI_CS_WORD) && !(ctlr->mode_bits & SPI_CS_WORD)) {

Then we could drop the error above.

>
>> + }
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
>

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