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SubjectRe: [PATCH RFC 2/2] staging: fbtft: fix 9-bit SPI support detection
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Den 24.08.2015 20:33, skrev Stefan Wahren:
> Since bits_per_word isn't usually checked during SPI setup the 9-bit
> support must be checked manually.
>
> Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
> ---
> drivers/staging/fbtft/fbtft-core.c | 7 +++++++
> drivers/staging/fbtft/flexfb.c | 7 +++++++
> 2 files changed, 14 insertions(+)
>
> diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
> index 3638554..bd71487 100644
> --- a/drivers/staging/fbtft/fbtft-core.c
> +++ b/drivers/staging/fbtft/fbtft-core.c
> @@ -1438,6 +1438,13 @@ int fbtft_probe_common(struct fbtft_display *display,
> if (par->spi && display->buswidth == 9) {
> par->spi->bits_per_word = 9;
> ret = spi_setup(par->spi);
> + if (!ret) {
> + struct spi_master *ma = par->spi->master;
> +
> + if (!(ma->bits_per_word_mask & SPI_BPW_MASK(9)))
> + ret = -EINVAL;
> + }
> +
> if (ret) {

There's no point in calling spi_setup() when it doesn't check bits_per_word.
Apparently this changed with the commit:
spi: convert drivers to use bits_per_word_mask.
This has not been detected earlier, because FBTFT was previously mostly
used on the Raspberry Pi which had a downstream SPI driver that did this
check.

How about this:

- par->spi->bits_per_word = 9;
- ret = par->spi->master->setup(par->spi);
+ if (par->spi->master->bits_per_word_mask &
SPI_BPW_MASK(9)) {
+ par->spi->bits_per_word = 9;
- if (ret) {
+ } else {
dev_warn(&par->spi->dev,
"9-bit SPI not available, emulating
using 8-bit.\n");
- par->spi->bits_per_word = 8;
- ret = par->spi->master->setup(par->spi);
- if (ret)
- goto out_release;
/* allocate buffer with room for dc bits */
par->extra = devm_kzalloc(par->info->device,



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