[PATCH v4] drm: Add support for DP 1.4 Compliance edid corruption test 4.2.2.6

[Harry Wentland]

On 2019-11-25 4:36 p.m., Zuo, Jerry wrote:
> Please kindly give a review on my latest revision. Thanks a lot.
> 

Both patches are
Reviewed-by: Harry Wentland <harry.wentland at amd.com>

Harry

> Regards,
> Jerry
> 
> -----Original Message-----
> From: Jerry (Fangzhi) Zuo <Jerry.Zuo at amd.com> 
> Sent: November 5, 2019 11:38 AM
> To: dri-devel at lists.freedesktop.org; amd-gfx at lists.freedesktop.org
> Cc: lyude at redhat.com; manasi.d.navare at intel.com; Wentland, Harry <Harry.Wentland at amd.com>; Zuo, Jerry <Jerry.Zuo at amd.com>
> Subject: [PATCH v4] drm: Add support for DP 1.4 Compliance edid corruption test 4.2.2.6
> 
> DP 1.4 edid corruption test requires source DUT to write calculated CRC, not the corrupted CRC from reference sink.
> 
> Return the calculated CRC back, and initiate the required sequence.
> 
> -v2: Have separate routine for returning real CRC
> 
> -v3: Rewrite checksum computation routine to avoid duplicated code.
>      Rename to avoid confusion
> 
> -v4: Fix a minor typo.
> 
> Signed-off-by: Jerry (Fangzhi) Zuo <Jerry.Zuo at amd.com>
> ---
>  drivers/gpu/drm/drm_dp_helper.c | 36 ++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/drm_edid.c      | 18 +++++++++++++++---
>  include/drm/drm_connector.h     |  7 +++++++
>  include/drm/drm_dp_helper.h     |  3 +++
>  4 files changed, 61 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index ffc68d305afe..22a0e966ea9f 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -336,6 +336,42 @@ int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,  }  EXPORT_SYMBOL(drm_dp_dpcd_read_link_status);
>  
> +/**
> +  * drm_dp_send_real_edid_checksum() - send back real edid checksum 
> +value
> +  * @aux: DisplayPort AUX channel
> +  * @real_edid_checksum: real edid checksum for the last block
> +  *
> +  * Returns true on success
> +  */
> +bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux,
> +                                u8 real_edid_checksum) {
> +        u8 link_edid_read = 0, auto_test_req = 0;
> +        u8 test_resp = 0;
> +
> +        drm_dp_dpcd_read(aux, DP_DEVICE_SERVICE_IRQ_VECTOR, &auto_test_req, 1);
> +        auto_test_req &= DP_AUTOMATED_TEST_REQUEST;
> +
> +        drm_dp_dpcd_read(aux, DP_TEST_REQUEST, &link_edid_read, 1);
> +        link_edid_read &= DP_TEST_LINK_EDID_READ;
> +
> +        if (!auto_test_req || !link_edid_read) {
> +                DRM_DEBUG_KMS("Source DUT does not support TEST_EDID_READ\n");
> +                return false;
> +        }
> +
> +        drm_dp_dpcd_write(aux, DP_DEVICE_SERVICE_IRQ_VECTOR, 
> + &auto_test_req, 1);
> +
> +        /* send back checksum for the last edid extension block data */
> +        drm_dp_dpcd_write(aux, DP_TEST_EDID_CHECKSUM, 
> + &real_edid_checksum, 1);
> +
> +        test_resp |= DP_TEST_EDID_CHECKSUM_WRITE;
> +        drm_dp_dpcd_write(aux, DP_TEST_RESPONSE, &test_resp, 1);
> +
> +        return true;
> +}
> +EXPORT_SYMBOL(drm_dp_send_real_edid_checksum);
> +
>  /**
>   * drm_dp_link_probe() - probe a DisplayPort link for capabilities
>   * @aux: DisplayPort AUX channel
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index 82a4ceed3fcf..ff64e5f1feb6 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -1348,10 +1348,19 @@ static int drm_edid_block_checksum(const u8 *raw_edid)  {
>  	int i;
>  	u8 csum = 0;
> -	for (i = 0; i < EDID_LENGTH; i++)
> +
> +	for (i = 0; i < EDID_LENGTH - 1; i++)
>  		csum += raw_edid[i];
>  
> -	return csum;
> +	return (0x100 - csum);
> +}
> +
> +static bool drm_edid_block_checksum_diff(const u8 *raw_edid, u8 
> +real_checksum) {
> +	if (raw_edid[EDID_LENGTH - 1] != real_checksum)
> +		return true;
> +	else
> +		return false;
>  }
>  
>  static bool drm_edid_is_zero(const u8 *in_edid, int length) @@ -1409,7 +1418,7 @@ bool drm_edid_block_valid(u8 *raw_edid, int block, bool print_bad_edid,
>  	}
>  
>  	csum = drm_edid_block_checksum(raw_edid);
> -	if (csum) {
> +	if (drm_edid_block_checksum_diff(raw_edid, csum)) {
>  		if (edid_corrupt)
>  			*edid_corrupt = true;
>  
> @@ -1572,6 +1581,9 @@ static void connector_bad_edid(struct drm_connector *connector,
>  			       prefix, DUMP_PREFIX_NONE, 16, 1,
>  			       block, EDID_LENGTH, false);
>  	}
> +
> +	/* Calculate real checksum for the last edid extension block data */
> +	connector->real_edid_checksum = drm_edid_block_checksum(edid + 
> +edid[0x7e] * EDID_LENGTH);
>  }
>  
>  /* Get override or firmware EDID */
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h index 681cb590f952..eb0d8c7b35fd 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -1345,6 +1345,13 @@ struct drm_connector {
>  	 * rev1.1 4.2.2.6
>  	 */
>  	bool edid_corrupt;
> +	/**
> +         * @real_edid_checksum: real edid checksum value for corrupted edid block.
> +         * Required in Displayport 1.4 compliance testing
> +         * rev1.1 4.2.2.6
> +         */
> +        uint8_t real_edid_checksum;
> +
>  
>  	/** @debugfs_entry: debugfs directory for this connector */
>  	struct dentry *debugfs_entry;
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 5a795075d5da..84709d7810f8 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -1383,6 +1383,9 @@ static inline ssize_t drm_dp_dpcd_writeb(struct drm_dp_aux *aux,  int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
>  				 u8 status[DP_LINK_STATUS_SIZE]);
>  
> +bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux,
> +				    u8 real_edid_checksum);
> +
>  /*
>   * DisplayPort link
>   */
> --
> 2.14.1
>