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

["Frank Schäfer" <fschaefer.oss@googlemail.com>]

Am 24.03.2013 12:44, schrieb Mauro Carvalho Chehab:
> 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: align width+height to multiples of 4 ?! */
> 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);
> 	}

Ok, no problem.

Frank

>
>>  }
>>  
>>  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
>>  
>