On Fri, Jul 03, 2020 at 04:13:41PM +0200, Paul Cercueil wrote: > The function mipi_dbi_spi1_transfer() will transfer its payload as 9-bit > data, the 9th (MSB) bit being the data/command bit. In order to do that, > it unpacks the 8-bit values into 16-bit values, then sets the 9th bit if > the byte corresponds to data, clears it otherwise. The 7 MSB are > padding. The array of now 16-bit values is then passed to the SPI core > for transfer. > > This function was broken since its introduction, as the length of the > SPI transfer was set to the payload size before its conversion, but the > payload doubled in size due to the 8-bit -> 16-bit conversion. > > Fixes: 02dd95fe3169 ("drm/tinydrm: Add MIPI DBI support") > Cc: <stable@xxxxxxxxxxxxxxx> # 4.10 > Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx> As discussed on irc this looks correct to me too. Reviewed-by: Sam Ravnborg <sam@xxxxxxxxxxxx> I will apply later, but let's wait and see if Noralf or others have any feedback first. Sam > --- > drivers/gpu/drm/drm_mipi_dbi.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_mipi_dbi.c b/drivers/gpu/drm/drm_mipi_dbi.c > index bb27c82757f1..bf7888ad9ad4 100644 > --- a/drivers/gpu/drm/drm_mipi_dbi.c > +++ b/drivers/gpu/drm/drm_mipi_dbi.c > @@ -923,7 +923,7 @@ static int mipi_dbi_spi1_transfer(struct mipi_dbi *dbi, int dc, > } > } > > - tr.len = chunk; > + tr.len = chunk * 2; > len -= chunk; > > ret = spi_sync(spi, &m); > -- > 2.27.0 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel