Re: [PATCH v2 5/5] em28xx: write output frame resolution to regs 0x34+0x35 for em25xx family bridges

[Mauro Carvalho Chehab <mchehab@redhat.com>]

Em Sat, 23 Mar 2013 18:27:12 +0100
Frank Schäfer <fschaefer.oss@googlemail.com> 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@googlemail.com>
> ---
>  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