Re: [PATCH] em28xx: overhaul em28xx_capture_area_set()

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

Am 05.02.2013 23:48, schrieb Mauro Carvalho Chehab:
> Em Sun, 20 Jan 2013 14:26:47 +0100
> Frank Schäfer <fschaefer.oss@googlemail.com> escreveu:
>
>> - move the bit shifting of width+height values inside the function
>> - fix the debug message format and output values
>> - add comment about the size limit (e.g. EM277x supports >2MPix)
>> - make void, because error checking is incomplete and we never check the
>>   returned value (we would continue anyway)
>>
>> Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
>> ---
>>  drivers/media/usb/em28xx/em28xx-core.c |   22 ++++++++++++----------
>>  1 Datei geändert, 12 Zeilen hinzugefügt(+), 10 Zeilen entfernt(-)
>>
>> diff --git a/drivers/media/usb/em28xx/em28xx-core.c b/drivers/media/usb/em28xx/em28xx-core.c
>> index 210859a..f516a63 100644
>> --- a/drivers/media/usb/em28xx/em28xx-core.c
>> +++ b/drivers/media/usb/em28xx/em28xx-core.c
>> @@ -733,22 +733,24 @@ static int em28xx_accumulator_set(struct em28xx *dev, u8 xmin, u8 xmax,
>>  	return em28xx_write_regs(dev, EM28XX_R2B_YMAX, &ymax, 1);
>>  }
>>  
>> -static int em28xx_capture_area_set(struct em28xx *dev, u8 hstart, u8 vstart,
>> +static void em28xx_capture_area_set(struct em28xx *dev, u8 hstart, u8 vstart,
>>  				   u16 width, u16 height)
>>  {
>> -	u8 cwidth = width;
>> -	u8 cheight = height;
>> -	u8 overflow = (height >> 7 & 0x02) | (width >> 8 & 0x01);
>> +	u8 cwidth = width >> 2;
>> +	u8 cheight = height >> 2;
>> +	u8 overflow = (height >> 9 & 0x02) | (width >> 10 & 0x01);
> Hmm.. why did you change the above overflow bits?

Read the complete patch, the answer is...
...

>  That change doesn't
> sound right to me. Ok, I don't have the datasheets, so I might be
> wrong, but if is there a bug there, please submit the bug fix into a
> separate patch, clearly explaining why such change is needed.
>
>> +	/* NOTE: size limit: 2047x1023 = 2MPix */
>>  
>> -	em28xx_coredbg("em28xx Area Set: (%d,%d)\n",
>> -			(width | (overflow & 2) << 7),
>> -			(height | (overflow & 1) << 8));
>> +	em28xx_coredbg("capture area set to (%d,%d): %dx%d\n",
>> +		       hstart, vstart,
>> +		       ((overflow & 2) << 9 | cwidth << 2),
>> +		       ((overflow & 1) << 10 | cheight << 2));
>>  
>>  	em28xx_write_regs(dev, EM28XX_R1C_HSTART, &hstart, 1);
>>  	em28xx_write_regs(dev, EM28XX_R1D_VSTART, &vstart, 1);
>>  	em28xx_write_regs(dev, EM28XX_R1E_CWIDTH, &cwidth, 1);
>>  	em28xx_write_regs(dev, EM28XX_R1F_CHEIGHT, &cheight, 1);
>> -	return em28xx_write_regs(dev, EM28XX_R1B_OFLOW, &overflow, 1);
>> +	em28xx_write_regs(dev, EM28XX_R1B_OFLOW, &overflow, 1);
>>  }
>>  
>>  static int em28xx_scaler_set(struct em28xx *dev, u16 h, u16 v)
>> @@ -801,9 +803,9 @@ int em28xx_resolution_set(struct em28xx *dev)
>>  	   it out, we end up with the same format as the rest of the VBI
>>  	   region */
>>  	if (em28xx_vbi_supported(dev) == 1)
>> -		em28xx_capture_area_set(dev, 0, 2, width >> 2, height >> 2);
>> +		em28xx_capture_area_set(dev, 0, 2, width, height);
>>  	else
>> -		em28xx_capture_area_set(dev, 0, 0, width >> 2, height >> 2);
>> +		em28xx_capture_area_set(dev, 0, 0, width, height);

... here !
So it's not a real change.

Regards,
Frank

>>  
>>  	return em28xx_scaler_set(dev, dev->hscale, dev->vscale);
>>  }