[PATCH 16/20] drm: add function to read vendor OUI

[Sharma, Shashank]

Regads

Shashank


On 7/12/2017 10:45 PM, Ville Syrjälä wrote:
> On Mon, Jul 10, 2017 at 04:48:44PM +0530, Shashank Sharma wrote:
>> This patch adds a helper function in DP dual mode layer to
>> read the vendor's IEEE OUI signature from a Dual mode adapter.
>> This will be used to differentiate between different LSPCON
>> vendors, to address their custom programming requirements.
> Can't we just read it from DPCD instead?
You are right, as we have DPCD cached, we can do it from DPCD too, and 
in fact that was my first implementation.
But then I thought what if some driver doesn't cache DPCD, so thought it 
would be good to have a helper function
to check this out.
If you think DPCD would be a better idea, I need not to touch DRM layer 
at all, and this will be only I915 implementation.

- Shashank
>
>> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> Cc: Imre Deak <imre.deak at intel.com>
>> Signed-off-by: Shashank Sharma <shashank.sharma at intel.com>
>> ---
>>   drivers/gpu/drm/drm_dp_dual_mode_helper.c | 24 ++++++++++++++++++++++++
>>   include/drm/drm_dp_dual_mode_helper.h     |  4 +++-
>>   2 files changed, 27 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>> index 80e62f6..0b890dc 100644
>> --- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>> +++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>> @@ -396,6 +396,30 @@ const char *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type type)
>>   EXPORT_SYMBOL(drm_dp_get_dual_mode_type_name);
>>   
>>   /**
>> + * drm_lspcon_get_vendor_oui: match vendor OUI signature
>> + * @adapter: i2c adapter under action
>> + * @vendor_id = 3 bytes of vendor OUI signature, LSB=lower byte
>> + *
>> + * Returns:
>> + * Vendor OUI id if got one, 0 if not
>> + */
>> +uint32_t drm_lspcon_get_vendor_oui(struct i2c_adapter *adapter)
>> +{
>> +	uint8_t sign[3] = {0, };
>> +	uint32_t oui = 0;
>> +
>> +	if (drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_LSPCON_OUI_OFFSET,
>> +						sign, 3)) {
>> +		DRM_ERROR("Can't identify vendor sign\n");
>> +		return 0;
>> +	}
>> +
>> +	oui = (sign[0] << 16) | (sign[1] << 8) | sign[2];
>> +	return oui;
>> +}
>> +EXPORT_SYMBOL(drm_lspcon_get_vendor_oui);
>> +
>> +/**
>>    * drm_lspcon_get_mode: Get LSPCON's current mode of operation by
>>    * reading offset (0x80, 0x41)
>>    * @adapter: I2C-over-aux adapter
>> diff --git a/include/drm/drm_dp_dual_mode_helper.h b/include/drm/drm_dp_dual_mode_helper.h
>> index 4c42db8..f81b526 100644
>> --- a/include/drm/drm_dp_dual_mode_helper.h
>> +++ b/include/drm/drm_dp_dual_mode_helper.h
>> @@ -60,7 +60,8 @@
>>   /* LSPCON specific registers, defined by MCA */
>>   #define DP_DUAL_MODE_LSPCON_MODE_CHANGE		0x40
>>   #define DP_DUAL_MODE_LSPCON_CURRENT_MODE		0x41
>> -#define  DP_DUAL_MODE_LSPCON_MODE_PCON			0x1
>> +#define DP_DUAL_MODE_LSPCON_MODE_PCON			0x1
>> +#define DP_DUAL_MODE_LSPCON_OUI_OFFSET			0x11
>>   
>>   struct i2c_adapter;
>>   
>> @@ -116,4 +117,5 @@ int drm_lspcon_get_mode(struct i2c_adapter *adapter,
>>   			enum drm_lspcon_mode *current_mode);
>>   int drm_lspcon_set_mode(struct i2c_adapter *adapter,
>>   			enum drm_lspcon_mode reqd_mode);
>> +uint32_t drm_lspcon_get_vendor_oui(struct i2c_adapter *adapter);
>>   #endif
>> -- 
>> 2.7.4