[Intel-gfx] [PATCH] drm/i915: Update HDMI max TMDS data rate definition for VBT

[Ville Syrjälä]

On Wed, Apr 10, 2019 at 11:32:47AM +0000, Chiou, Cooper wrote:
> Hi Ville,
> 
> 
> 
> From BSpec define, HDMI max data rate is “Bits 5-7” not Bits 4-7. And the following image is what I captured by latest VBT BMP v2.67 tool to load GLK VBT bin file and changed HDMI_MAX_TMDS_Bit_Rate field in 5.94/2.97/1.65Gbps different bit-rate.
> 
> 
> 
> A. 5.94Gbps(HDMI_MAX_DATA_RATE_PLATFORM) = 0 is correct, the “HDMI max data rate and level shift” value is 0x08 in following highlight block.
> 
> 
> 
> B. 2.97Gbps (HDMI_MAX_DATA_RATE_297) was 1 is wrong, it should be 001x xxxx. In this case, “HDMI max data rate and level shift value” is “0x28” in vbt.bin, so intel_vbt_defs.h HDMI_MAX_DATA_RATE_297=1 is wrong, so it should be 2

No. Read the struct definition:
struct child_device_config {
        u16 handle;
        u16 device_type; /* See DEVICE_TYPE_* above */

        union {
               	u8  device_id[10]; /* ascii string */
                struct {
                        u8 i2c_speed;
                        u8 dp_onboard_redriver;                 /* 158 */
                        u8 dp_ondock_redriver;                  /* 158 */
                        u8 hdmi_level_shifter_value:5;          /* 169 */
                        u8 hdmi_max_data_rate:3;                /* 204 */

That bitfield matches the spec.

-- 
Ville Syrjälä
Intel