From: Sean Paul <seanpaul@xxxxxxxxxxxx> Although the DisplayPort spec explicitly calls out the 1.62/2.7/5.4/8.1 link rates, the value of LINK_BW_SET is calculated. The DisplayPort spec says "Main-Link Bandwidth Setting = Value x 0.27Gbps/lane". A bridge that we're looking to upstream uses 6.75Gbps rate (value 0x19) [1], and that precludes it from using these functions. This patch calculates the values according to spec instead of restricting these values to one of the DP_LINK_BW_* #defines. No functional change for the well-defined values, but we lose the warning for ill-defined bw values. Signed-off-by: Sean Paul <seanpaul@xxxxxxxxxxxx> [1] https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1689251/2/drivers/gpu/drm/bridge/analogix/anx7625.c#636 --- drivers/gpu/drm/drm_dp_helper.c | 31 ++++--------------------------- 1 file changed, 4 insertions(+), 27 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 0b994d083a89..ffc68d305afe 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -152,38 +152,15 @@ EXPORT_SYMBOL(drm_dp_link_train_channel_eq_delay); u8 drm_dp_link_rate_to_bw_code(int link_rate) { - switch (link_rate) { - default: - WARN(1, "unknown DP link rate %d, using %x\n", link_rate, - DP_LINK_BW_1_62); - /* fall through */ - case 162000: - return DP_LINK_BW_1_62; - case 270000: - return DP_LINK_BW_2_7; - case 540000: - return DP_LINK_BW_5_4; - case 810000: - return DP_LINK_BW_8_1; - } + /* Spec says link_bw = link_rate / 0.27Gbps */ + return link_rate / 27000; } EXPORT_SYMBOL(drm_dp_link_rate_to_bw_code); int drm_dp_bw_code_to_link_rate(u8 link_bw) { - switch (link_bw) { - default: - WARN(1, "unknown DP link BW code %x, using 162000\n", link_bw); - /* fall through */ - case DP_LINK_BW_1_62: - return 162000; - case DP_LINK_BW_2_7: - return 270000; - case DP_LINK_BW_5_4: - return 540000; - case DP_LINK_BW_8_1: - return 810000; - } + /* Spec says link_rate = link_bw * 0.27Gbps */ + return link_bw * 27000; } EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate); -- Sean Paul, Software Engineer, Google / Chromium OS _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
