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

[Dhinakaran Pandiyan]

On Mon, 2018-09-10 at 08:26 -0700, Lee, Shawn C 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? 

>  	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