Den 25.08.2015 19:34, skrev Stefan Wahren:
Noralf Trønnes <noralf@xxxxxxxxxxx> hat am 25. August 2015 um 00:00
geschrieben:
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@xxxxxxxx>
---
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.
If checking of bits_per_word is the only intention of the setup call, then i
agree.
But i'm not sure it is safe to remove the setup call complete.
Couldn't this cause regressions since there is no common spi setup call for all
drivers?
spi_add_device() calls spi_setup() for all spi devices so it's already done.
If spi_setup() did something with bits_per_word, then I agree that we should
call it in the 9-bit case. But this is not the case, and it's possible to
change bits_per_word per transfer later, so I can't see that this is needed.
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;
I think this assignment should stay.
Not needed since we haven't changed the default set by spi_setup():
if (!spi->bits_per_word)
spi->bits_per_word = 8;
Callchain for DT registered spi devices:
spi_register_master->of_register_spi_devices->of_register_spi_device->
spi_add_device->spi_setup
_______________________________________________
devel mailing list
devel@xxxxxxxxxxxxxxxxxxxxxx
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
