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

["Sharma, Shashank" <shashank.sharma@intel.com>]

Regards

Shashank


On 7/13/2017 6:07 PM, Ville Syrjälä wrote:
> On Thu, Jul 13, 2017 at 10:34:26AM +0530, Sharma, Shashank wrote:
>> 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.
> Yeah, less code seems like a good thing. I think we might even have that
> OUI stuff already read out and cached for other purposes.
Sure, then, I will extract OUI and cache it in a variable.
- Shashank
>> - Shashank
>>>> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>>> Cc: Imre Deak <imre.deak@intel.com>
>>>> Signed-off-by: Shashank Sharma <shashank.sharma@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

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