# Re: \[PATCH 4/4\] fb: vt8500: Add VGA output support to wm8505fb driver.

- From: Andy Chernyak \<hidden\>
- Date: 2013-05-18 13:41:51 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2013/05/4051604
- Thread: https://ratatoskr.run/linux-arm-kernel/2013/05/4051584/t.md

```text
On 05/18/2013 03:28 PM, Alexey Charkov wrote:
> 2013/5/18 Tony Prisk [ref]:
>
>>         /* Virtual buffer size */
>> @@ -167,7 +176,12 @@ static int wm8505fb_init_hw(struct fb_info *info)
>>
>>         /* black magic ;) */
>>         writel(0xf,                    fbi->regbase + REG_GOVRH_FHI);
>> -       writel(4,                      fbi->regbase + REG_GOVRH_DVO_SET);
>> +
>> +       if (fbi->interface = INTERFACE_VGA)
>> +               writel(0xe, fbi->regbase + REG_GOVRH_DVO_SET);
>> +       else
>> +               writel(4, fbi->regbase + REG_GOVRH_DVO_SET);
> I don't remember if HDMI is yet another option for this register or
> not... If it is, it would probably warrant defining fbi->interface as
> an enum and changing this if-else into a switch statement to let the
> compiler add its checks/warnings.
HDMI output can work simultaneously with LCD (on 8850 at least), which
fbi->interface in its current form would not allow to express.

> +       if (fbi->interface = INTERFACE_VGA)
> +               writel(h_sync,  fbi->regbase + REG_GOVRH_VGA_HSYNW);
> Will it misbehave on LCD if you write to the VGA register unconditionally?
>
Can we have 3 flags, something like LCD_ON, VGA_ON, HDMI_ON instead of
enum for video interface selection?

Regards,
Andy.
```