diff options
| author |   Linus Walleij <linus.walleij@linaro.org> | 2020-11-11 00:46:51 +0100 |
|---|---|---|
| committer | Linus Walleij <linus.walleij@linaro.org> | 2020-11-16 00:48:16 +0100 |
| commit | 9cea169835dec8faa1be0e980b2ed9da7e2c9850 (patch) | |
| tree | ac20bf33518992b58e35ecb56a068338703f58bd | |
| parent | drm/panel: s6e63m0: Implement reading from panel (diff) | |
| download | linux-dev-9cea169835dec8faa1be0e980b2ed9da7e2c9850.tar.xz linux-dev-9cea169835dec8faa1be0e980b2ed9da7e2c9850.zip | |
drm/panel: s6e63m0: Add some explanations
The SPI DCS code was a bit hard to understand as the
device accepts 9-bit transfers packed into 16-bit words
with the most significant bit in bit 9 of the
16-bit word. Add some clarifying comments.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Stephan Gerhold <stephan@gerhold.net>
Cc: Paweł Chmiel <pawel.mikolaj.chmiel@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201110234653.2248594-4-linus.walleij@linaro.org
| -rw-r--r-- | drivers/gpu/drm/panel/panel-samsung-s6e63m0-spi.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/gpu/drm/panel/panel-samsung-s6e63m0-spi.c b/drivers/gpu/drm/panel/panel-samsung-s6e63m0-spi.c index 94ae4ac5a88e..fa24e6889ec1 100644 --- a/drivers/gpu/drm/panel/panel-samsung-s6e63m0-spi.c +++ b/drivers/gpu/drm/panel/panel-samsung-s6e63m0-spi.c @@ -42,10 +42,17 @@ static int s6e63m0_spi_dcs_write(struct device *dev, const u8 *data, size_t len) int ret = 0; dev_dbg(dev, "SPI writing dcs seq: %*ph\n", (int)len, data); + + /* + * This sends 9 bits with the first bit (bit 8) set to 0 + * This indicates that this is a command. Anything after the + * command is data. + */ ret = s6e63m0_spi_write_word(dev, *data); while (!ret && --len) { ++data; + /* This sends 9 bits with the first bit (bit 8) set to 1 */ ret = s6e63m0_spi_write_word(dev, *data | DATA_MASK); } |