[Intel-gfx] [PATCH v3 01/13] drm/dp: add DP 2.0 UHBR link rate and bw code conversions

Jani Nikula
2021-09-09T12:52:26Z

The bw code equals link_rate / 0.27 Gbps only for 8b/10b link
rates. Handle DP 2.0 UHBR rates as special cases, though this is not
pretty.

Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
drivers/gpu/drm/drm_dp_helper.c | 26 ++++++++++++++++++++++----
1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 6d0f2c447f3b..9b2a2961fca8 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -207,15 +207,33 @@ EXPORT_SYMBOL(drm_dp_lttpr_link_train_channel_eq_delay);

u8 drm_dp_link_rate_to_bw_code(int link_rate)
{
- /* Spec says link_bw = link_rate / 0.27Gbps */
- return link_rate / 27000;
+ switch (link_rate) {
+ case 1000000:
+ return DP_LINK_BW_10;
+ case 1350000:
+ return DP_LINK_BW_13_5;
+ case 2000000:
+ return DP_LINK_BW_20;
+ default:
+ /* 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)
{
- /* Spec says link_rate = link_bw * 0.27Gbps */
- return link_bw * 27000;
+ switch (link_bw) {
+ case DP_LINK_BW_10:
+ return 1000000;
+ case DP_LINK_BW_13_5:
+ return 1350000;
+ case DP_LINK_BW_20:
+ return 2000000;
+ default:
+ /* Spec says link_rate = link_bw * 0.27Gbps */
+ return link_bw * 27000;
+ }
}
EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);

--
2.30.2