From: Linus Walleij Date: Tue, 10 Nov 2020 23:46:51 +0000 (+0100) Subject: drm/panel: s6e63m0: Add some explanations X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=9cea169835dec8faa1be0e980b2ed9da7e2c9850;p=linux.git 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 Acked-by: Sam Ravnborg Cc: Stephan Gerhold Cc: Paweł Chmiel Link: https://patchwork.freedesktop.org/patch/msgid/20201110234653.2248594-4-linus.walleij@linaro.org --- diff --git a/drivers/gpu/drm/panel/panel-samsung-s6e63m0-spi.c b/drivers/gpu/drm/panel/panel-samsung-s6e63m0-spi.c index 94ae4ac5a88ed..fa24e6889ec18 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); }