Re: [PATCH v3 2/9] drm/dp: get/set phy compliance pattern

[Harry Wentland <hwentlan@amd.com>]

On 2019-12-23 12:03 p.m., Animesh Manna wrote:
> During phy compliance auto test mode source need to read
> requested test pattern from sink through DPCD. After processing
> the request source need to set the pattern. So set/get method
> added in drm layer as it is DP protocol.
> 
> v2: As per review feedback from Manasi on RFC version,
> - added dp revision as function argument in set_phy_pattern api.
> - used int for link_rate and u8 for lane_count to align with existing code.
> 
> Signed-off-by: Animesh Manna <animesh.manna@intel.com>
> ---
>  drivers/gpu/drm/drm_dp_helper.c | 93 +++++++++++++++++++++++++++++++++
>  include/drm/drm_dp_helper.h     | 31 +++++++++++
>  2 files changed, 124 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index 2c7870aef469..91c80973aa83 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -1371,3 +1371,96 @@ int drm_dp_dsc_sink_supported_input_bpcs(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_S
>  	return num_bpc;
>  }
>  EXPORT_SYMBOL(drm_dp_dsc_sink_supported_input_bpcs);
> +
> +/**
> + * drm_dp_get_phy_test_pattern() - get the requested pattern from the sink.
> + * @aux: DisplayPort AUX channel
> + * @data: DP phy compliance test parameters.
> + *
> + * Returns 0 on success or a negative error code on failure.
> + */
> +int drm_dp_get_phy_test_pattern(struct drm_dp_aux *aux,
> +				struct drm_dp_phy_test_params *data)
> +{
> +	int err;
> +	u8 rate, lanes;
> +
> +	err = drm_dp_dpcd_readb(aux, DP_TEST_LINK_RATE, &rate);
> +	if (err < 0)
> +		return err;
> +	data->link_rate = drm_dp_bw_code_to_link_rate(rate);
> +
> +	err = drm_dp_dpcd_readb(aux, DP_TEST_LANE_COUNT, &lanes);
> +	if (err < 0)
> +		return err;
> +	data->num_lanes = lanes & DP_MAX_LANE_COUNT_MASK;
> +
> +	if (lanes & DP_ENHANCED_FRAME_CAP)
> +		data->enahanced_frame_cap = true;
> +
> +	err = drm_dp_dpcd_readb(aux, DP_PHY_TEST_PATTERN, &data->phy_pattern);
> +	if (err < 0)
> +		return err;
> +
> +	switch (data->phy_pattern) {
> +	case DP_PHY_TEST_PATTERN_80BIT_CUSTOM:
> +		err = drm_dp_dpcd_read(aux, DP_TEST_80BIT_CUSTOM_PATTERN_7_0,
> +				       &data->custom80, 10);

Using sizeof(data->custom80) might be safer.

> +		if (err < 0)
> +			return err;
> +
> +		break;
> +	case DP_PHY_TEST_PATTERN_CP2520:
> +		err = drm_dp_dpcd_read(aux, DP_TEST_HBR2_SCRAMBLER_RESET,
> +				       &data->hbr2_reset, 2);

Same here, using sizeof(data->hbr2_reset).

> +		if (err < 0)
> +			return err;
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(drm_dp_get_phy_test_pattern);
> +
> +/**
> + * drm_dp_set_phy_test_pattern() - set the pattern to the sink.
> + * @aux: DisplayPort AUX channel
> + * @data: DP phy compliance test parameters.
> + *
> + * Returns 0 on success or a negative error code on failure.
> + */
> +int drm_dp_set_phy_test_pattern(struct drm_dp_aux *aux,
> +				struct drm_dp_phy_test_params *data, u8 dp_rev)
> +{
> +	int err, i;
> +	u8 link_config[2];
> +	u8 test_pattern;
> +
> +	link_config[0] = drm_dp_link_rate_to_bw_code(data->link_rate);
> +	link_config[1] = data->num_lanes;
> +	if (data->enahanced_frame_cap)
> +		link_config[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
> +	err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, link_config, 2);
> +	if (err < 0)
> +		return err;
> +
> +	test_pattern = data->phy_pattern;
> +	if (dp_rev < 0x12) {
> +		test_pattern = (test_pattern << 2) &
> +			       DP_LINK_QUAL_PATTERN_11_MASK;
> +		err = drm_dp_dpcd_writeb(aux, DP_TRAINING_PATTERN_SET,
> +					 test_pattern);
> +		if (err < 0)
> +			return err;
> +	} else {
> +		for (i = 0; i < data->num_lanes; i++) {
> +			err = drm_dp_dpcd_writeb(aux,
> +						 DP_LINK_QUAL_LANE0_SET + i,
> +						 test_pattern);
> +			if (err < 0)
> +				return err;
> +		}
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(drm_dp_set_phy_test_pattern);
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index d6e560870fb1..42a364748308 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -700,6 +700,15 @@
>  # define DP_TEST_COUNT_MASK		    0xf
>  
>  #define DP_PHY_TEST_PATTERN                 0x248
> +# define DP_PHY_TEST_PATTERN_SEL_MASK       0x7
> +# define DP_PHY_TEST_PATTERN_NONE           0x0
> +# define DP_PHY_TEST_PATTERN_D10_2          0x1
> +# define DP_PHY_TEST_PATTERN_ERROR_COUNT    0x2
> +# define DP_PHY_TEST_PATTERN_PRBS7          0x3
> +# define DP_PHY_TEST_PATTERN_80BIT_CUSTOM   0x4
> +# define DP_PHY_TEST_PATTERN_CP2520         0x5
> +
> +#define DP_TEST_HBR2_SCRAMBLER_RESET        0x24A
>  #define DP_TEST_80BIT_CUSTOM_PATTERN_7_0    0x250
>  #define	DP_TEST_80BIT_CUSTOM_PATTERN_15_8   0x251
>  #define	DP_TEST_80BIT_CUSTOM_PATTERN_23_16  0x252
> @@ -1570,4 +1579,26 @@ static inline void drm_dp_cec_unset_edid(struct drm_dp_aux *aux)
>  
>  #endif
>  
> +/**
> + * struct drm_dp_phy_test_params - DP Phy Compliance parameters
> + * @link: Link information.

@link seems to be from a previous patch version. Please describe
link_rate and num_lanes instead.

> + * @phy_pattern: DP Phy test pattern from DPCD 0x248 (sink)
> + * @hb2_reset: DP HBR2_COMPLIANCE_SCRAMBLER_RESET from DCPD
> + *            0x24A and 0x24B (sink)
> + * @custom80: DP Test_80BIT_CUSTOM_PATTERN from DPCDs 0x250
> + *               through 0x259.

Missing doc for enhanced_frame_cap.

> + */
> +struct drm_dp_phy_test_params {
> +	int link_rate;

Is there a reason you're not using u8 here? Would be nice to keep it
consistent with num_lanes.

> +	u8 num_lanes;
> +	u8 phy_pattern;
> +	u8 hbr2_reset[2];
> +	u8 custom80[10];
> +	bool enahanced_frame_cap;

Typo. Should be enhanved_frame_cap.

Harry

> +};
> +
> +int drm_dp_get_phy_test_pattern(struct drm_dp_aux *aux,
> +				struct drm_dp_phy_test_params *data);
> +int drm_dp_set_phy_test_pattern(struct drm_dp_aux *aux,
> +				struct drm_dp_phy_test_params *data, u8 dp_rev);
>  #endif /* _DRM_DP_HELPER_H_ */
> 
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