On 2019-11-01 3:38 p.m., Jerry (Fangzhi) Zuo wrote:
> 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
>
> Signed-off-by: Jerry (Fangzhi) Zuo <Jerry.Zuo@xxxxxxx>
> ---
> drivers/gpu/drm/drm_dp_helper.c | 36 ++++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/drm_edid.c | 14 ++++++++++++++
> include/drm/drm_connector.h | 7 +++++++
> include/drm/drm_dp_helper.h | 3 +++
> 4 files changed, 60 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index ffc68d305afe..75dbd30c62a7 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_bad_edid_checksum() - send back real edid checksum value
> + * @aux: DisplayPort AUX channel
> + * @bad_edid_checksum: real edid checksum for the last block
> + *
> + * Returns true on success
> + */
> +bool drm_dp_send_bad_edid_checksum(struct drm_dp_aux *aux,
> + u8 bad_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, &bad_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_bad_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..0598314e3f46 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -1354,6 +1354,17 @@ static int drm_edid_block_checksum(const u8 *raw_edid)
> return csum;
> }
>
> +static int drm_edid_block_real_checksum(const u8 *raw_edid)
> +{
> + int i;
> + u8 csum = 0;
> +
> + for (i = 0; i < EDID_LENGTH - 1; i++)
> + csum += raw_edid[i];
> +
> + return (0x100 - csum);
> +}
> +
> static bool drm_edid_is_zero(const u8 *in_edid, int length)
> {
> if (memchr_inv(in_edid, 0, length))
> @@ -1572,6 +1583,9 @@ 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->bad_edid_checksum = drm_edid_block_real_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..8442461542b9 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;
> + /**
> + * @bad_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 bad_edid_checksum;
This variable name confused me a bit. Maybe name this
"computed_edid_checksum" to clarify that this is the EDID checksum that
we've computed for the EDID, i.e. the correct one.
> +
>
> /** @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..2a7e54bebb18 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_bad_edid_checksum(struct drm_dp_aux *aux,
Same as before, might be good to name this
drm_dp_send_computed_edid_checksum or something similar.
Harry
> + u8 bad_edid_checksum);
> +
> /*
> * DisplayPort link
> */
>
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