Em Sat, 23 Mar 2013 18:27:12 +0100
Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx> escreveu:
> The Windows driver writes the output resolution to registers 0x34 (width / 16)
> and 0x35 (height / 16) always.
> We don't know yet what these registers are used for.
>
> Signed-off-by: Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx>
> ---
> drivers/media/usb/em28xx/em28xx-core.c | 7 +++++++
> drivers/media/usb/em28xx/em28xx-reg.h | 6 ++++++
> 2 Dateien geändert, 13 Zeilen hinzugefügt(+)
>
> diff --git a/drivers/media/usb/em28xx/em28xx-core.c b/drivers/media/usb/em28xx/em28xx-core.c
> index 7b9f76b..0ce6b0f 100644
> --- a/drivers/media/usb/em28xx/em28xx-core.c
> +++ b/drivers/media/usb/em28xx/em28xx-core.c
> @@ -766,6 +766,13 @@ static void em28xx_capture_area_set(struct em28xx *dev, u8 hstart, u8 vstart,
> em28xx_write_regs(dev, EM28XX_R1E_CWIDTH, &cwidth, 1);
> em28xx_write_regs(dev, EM28XX_R1F_CHEIGHT, &cheight, 1);
> em28xx_write_regs(dev, EM28XX_R1B_OFLOW, &overflow, 1);
> +
> + if (dev->is_em25xx) {
> + em28xx_write_reg(dev, 0x34, width >> 4);
> + em28xx_write_reg(dev, 0x35, height >> 4);
> + }
> + /* FIXME: function/meaning of these registers ? */
> + /* FIXME: */
Please move those comments to be _before_ the code you're commenting.
E. g. something like:
if (dev->is_em25xx) {
/*
* FIXME:
* - function/meaning of these registers are unknown;
* - align width+height to multiples of 4 ?!
*/
em28xx_write_reg(dev, 0x34, width >> 4);
em28xx_write_reg(dev, 0x35, height >> 4);
}
> }
>
> static int em28xx_scaler_set(struct em28xx *dev, u16 h, u16 v)
> diff --git a/drivers/media/usb/em28xx/em28xx-reg.h b/drivers/media/usb/em28xx/em28xx-reg.h
> index 1b0ecd6..e08982a 100644
> --- a/drivers/media/usb/em28xx/em28xx-reg.h
> +++ b/drivers/media/usb/em28xx/em28xx-reg.h
> @@ -167,6 +167,12 @@
>
> #define EM28XX_R34_VBI_START_H 0x34
> #define EM28XX_R35_VBI_START_V 0x35
> +/* NOTE: the EM276x (and EM25xx, EM277x/8x ?) (camera bridges) use these
> + * registers for a different unknown purpose.
> + * => register 0x34 is set to capture width / 16
> + * => register 0x35 is set to capture height / 16
> + */
> +
> #define EM28XX_R36_VBI_WIDTH 0x36
> #define EM28XX_R37_VBI_HEIGHT 0x37
>
--
Cheers,
Mauro
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