[PATCH v2 1/3] drm: Add support for device_id based detection.

[Lee, Shawn C]

On Wed 9/12/2018 8:12 AM , Dhinakaran Pandiyan wrote:
>> DP quirk list just compare sink or branch device's OUI so far.
>> That means particular vendor's products will be applied specific 
>> change. This change would confirm device_id the same or not.
>> Then driver can implement some changes for branch/sink device that 
>> really need additional WA.
>> 
>> Cc: Jani Nikula <jani.nikula at intel.com>
>> Cc: Cooper Chiou <cooper.chiou at intel.com>
>> Cc: Matt Atwood <matthew.s.atwood at intel.com>
>> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
>> Cc: Clint Taylor <clinton.a.taylor at intel.com>
>> Signed-off-by: Lee, Shawn C <shawn.c.lee at intel.com>
>> ---
>>  drivers/gpu/drm/drm_dp_helper.c | 15 ++++++++++++++-
>>  1 file changed, 14 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/gpu/drm/drm_dp_helper.c 
>> b/drivers/gpu/drm/drm_dp_helper.c index 0cccbcb2d03e..0362c645d96e 
>> 100644
>> --- a/drivers/gpu/drm/drm_dp_helper.c
>> +++ b/drivers/gpu/drm/drm_dp_helper.c
>> @@ -1256,15 +1256,20 @@ EXPORT_SYMBOL(drm_dp_stop_crc);
>>  
>>  struct dpcd_quirk {
>>  	u8 oui[3];
>> +	u8 device_id[6];
>>  	bool is_branch;
>
>With device id included, do we still need is_branch? 
>

I think we should keep is_branch here. So far, this WA will be applied for all analogix
branch devices to fix multiple dongles can't display issue.

>>  	u32 quirks;
>>  };
>>  
>>  #define OUI(first, second, third) { (first), (second), (third) }
>> +#define DEVICE_ID(first, second, third, fourth, fifth, sixth) \
>> +	{ (first), (second), (third), (fourth), (fifth), (sixth) }
>> +
>> +#define DEVICE_ID_ANY	DEVICE_ID(0, 0, 0, 0, 0, 0)
>>  
>>  static const struct dpcd_quirk dpcd_quirk_list[] = {
>>  	/* Analogix 7737 needs reduced M and N at HBR2 link rates */
>> -	{ OUI(0x00, 0x22, 0xb9), true,
>> BIT(DP_DPCD_QUIRK_LIMITED_M_N) },
>> +	{ OUI(0x00, 0x22, 0xb9), DEVICE_ID_ANY, true,
>> BIT(DP_DPCD_QUIRK_LIMITED_M_N) },
>>  };
>>  
>>  #undef OUI
>> @@ -1283,6 +1288,7 @@ drm_dp_get_quirks(const struct drm_dp_dpcd_ident 
>> *ident, bool is_branch)
>>  	const struct dpcd_quirk *quirk;
>>  	u32 quirks = 0;
>>  	int i;
>> +	u8 any_device[] = DEVICE_ID_ANY;
>>  
>>  	for (i = 0; i < ARRAY_SIZE(dpcd_quirk_list); i++) {
>>  		quirk = &dpcd_quirk_list[i];
>> @@ -1293,12 +1299,19 @@ drm_dp_get_quirks(const struct 
>> drm_dp_dpcd_ident *ident, bool is_branch)
>
>Update documentation that currently says -
> "* For now, only the OUI (first three bytes) is used, but this may be extended
> * to device identification string ..."
>
>>  		if (memcmp(quirk->oui, ident->oui, sizeof(ident-
>> >oui)) != 0)
>>  			continue;
>>  
>> +		if (memcmp(quirk->device_id, any_device,
>> sizeof(any_device)) != 0 &&
>> +		    memcmp(quirk->device_id, ident->device_id,
>> sizeof(ident->device_id)) != 0)
>> +			continue;
>> +
>>  		quirks |= quirk->quirks;
>>  	}
>>  
>>  	return quirks;
>>  }
>>  
>> +#undef DEVICE_ID_ANY
>> +#undef DEVICE_ID
>> +
>>  /**
>>   * drm_dp_read_desc - read sink/branch descriptor from DPCD
>>   * @aux: DisplayPort AUX channel
>