[OpenPower-Firmware] [PATCH V3] Update VGA Ownership register value.

[Mamatha Inamdar]

On 07/19/2016 06:48 PM, Joel Stanley wrote:
> On Tue, Jun 28, 2016 at 4:31 AM, Mamatha Inamdar
> <mamatha4 at linux.vnet.ibm.com> wrote:
>> Problem Description:
>> Right now SCU2C: Control Register  values are not set correctly to enable VGA mode.
>> SCU2C register value is set to 0x00041080, where bit 18, 17,16 and bit 7 are set
>> to 1 which is CRT mode.
>>
>> Fix:
>> To enable VGA mode we have to set all register bit values to default values ie VGA mode.
>>
>> 1)  bit 18 in SCU2C register is to select  the DVO source for display output,
>>      by default it is VGA mode but it was set to 1(CRT mode).
>>
>>          18  RW Select the DVO source for display output
>>          0: VGA mode (default)
>>          1: Graphics CRT mode
>>
>> 2) bit 17 and 16 in SCU2C register is to select the DAC source for display output,
>>      by default it is VGA mode but it was set to 1(CRT mode).
>>          00: VGA mode
>>          01: Grafics CRT mode
>>          1X: pass-through DVO mode
>>
>> 2) second issue is  bit 7 in SCU2C register is to Enable 2D CRT Mode function as
>>     below and it was set to 1 as CRT mode.
>>
>>          7 Enable 2D CRT Mode function
>>          0: VGA mode (default)
>>          1: CRT mode
>>
>> The new value of SCU2C register is updated with mask value ~0x70080, which will enable
>> VGA mode by resetting bits 18,17,16 and 7 in SCU2C control register.
> I wasn't sure as to the context of this change. Is this new value
> something we want in the petitboot kernel for all systems?
Hi Joel,

This patch is to fix the issue raised in the bug 141248, yes this new 
value we want in the
petitboot kernel for BMC platforms,

>
> If so, I will need Jeremy ack before including it.
>
> Cheers,
>
> Joel

Jeremy,
Can you please ACK the patch
>
>> Signed-off-by: Mamatha Inamdar <mamatha4 at linux.vnet.ibm.com>
>> ---
>>   drivers/gpu/drm/ast/ast_post.c |    2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/ast/ast_post.c b/drivers/gpu/drm/ast/ast_post.c
>> index 703dba2..00ebe4f 100644
>> --- a/drivers/gpu/drm/ast/ast_post.c
>> +++ b/drivers/gpu/drm/ast/ast_post.c
>> @@ -1681,7 +1681,7 @@ static void ast_init_output_control(struct drm_device *dev)
>>                  break;
>>          default:
>>                  /* VGA only: enable DAC output */
>> -               val &= ~0x30000;
>> +               val &= ~0x70080;
>>                  break;
>>          }
>>
>>