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drm/radeon: fix dp link rate selection (v2)
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Need to properly handle the max link rate in the dpcd.
This prevents some cases where 5.4 Ghz is selected when
it shouldn't be.

v2: simplify logic, add array bounds check

Reviewed-by: Tom St Denis <tom.stdenis@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
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@alexdeucher
alexdeucher committed Dec 21, 2015
1 parent 41869c1 commit 092c96a
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Showing 3 changed files with 49 additions and 77 deletions.
108 changes: 36 additions & 72 deletions drivers/gpu/drm/radeon/atombios_dp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -302,77 +302,31 @@ static int convert_bpc_to_bpp(int bpc)
return bpc * 3;
}

/* get the max pix clock supported by the link rate and lane num */
static int dp_get_max_dp_pix_clock(int link_rate,
int lane_num,
int bpp)
{
return (link_rate * lane_num * 8) / bpp;
}

/***** radeon specific DP functions *****/

int radeon_dp_get_max_link_rate(struct drm_connector *connector,
const u8 dpcd[DP_DPCD_SIZE])
{
int max_link_rate;

if (radeon_connector_is_dp12_capable(connector))
max_link_rate = min(drm_dp_max_link_rate(dpcd), 540000);
else
max_link_rate = min(drm_dp_max_link_rate(dpcd), 270000);

return max_link_rate;
}

/* First get the min lane# when low rate is used according to pixel clock
* (prefer low rate), second check max lane# supported by DP panel,
* if the max lane# < low rate lane# then use max lane# instead.
*/
static int radeon_dp_get_dp_lane_number(struct drm_connector *connector,
const u8 dpcd[DP_DPCD_SIZE],
int pix_clock)
{
int bpp = convert_bpc_to_bpp(radeon_get_monitor_bpc(connector));
int max_link_rate = radeon_dp_get_max_link_rate(connector, dpcd);
int max_lane_num = drm_dp_max_lane_count(dpcd);
int lane_num;
int max_dp_pix_clock;

for (lane_num = 1; lane_num < max_lane_num; lane_num <<= 1) {
max_dp_pix_clock = dp_get_max_dp_pix_clock(max_link_rate, lane_num, bpp);
if (pix_clock <= max_dp_pix_clock)
break;
}

return lane_num;
}

static int radeon_dp_get_dp_link_clock(struct drm_connector *connector,
const u8 dpcd[DP_DPCD_SIZE],
int pix_clock)
int radeon_dp_get_dp_link_config(struct drm_connector *connector,
const u8 dpcd[DP_DPCD_SIZE],
unsigned pix_clock,
unsigned *dp_lanes, unsigned *dp_rate)
{
int bpp = convert_bpc_to_bpp(radeon_get_monitor_bpc(connector));
int lane_num, max_pix_clock;

if (radeon_connector_encoder_get_dp_bridge_encoder_id(connector) ==
ENCODER_OBJECT_ID_NUTMEG)
return 270000;

lane_num = radeon_dp_get_dp_lane_number(connector, dpcd, pix_clock);
max_pix_clock = dp_get_max_dp_pix_clock(162000, lane_num, bpp);
if (pix_clock <= max_pix_clock)
return 162000;
max_pix_clock = dp_get_max_dp_pix_clock(270000, lane_num, bpp);
if (pix_clock <= max_pix_clock)
return 270000;
if (radeon_connector_is_dp12_capable(connector)) {
max_pix_clock = dp_get_max_dp_pix_clock(540000, lane_num, bpp);
if (pix_clock <= max_pix_clock)
return 540000;
static const unsigned link_rates[3] = { 162000, 270000, 540000 };
unsigned max_link_rate = drm_dp_max_link_rate(dpcd);
unsigned max_lane_num = drm_dp_max_lane_count(dpcd);
unsigned lane_num, i, max_pix_clock;

for (lane_num = 1; lane_num <= max_lane_num; lane_num <<= 1) {
for (i = 0; i < ARRAY_SIZE(link_rates) && link_rates[i] <= max_link_rate; i++) {
max_pix_clock = (lane_num * link_rates[i] * 8) / bpp;
if (max_pix_clock >= pix_clock) {
*dp_lanes = lane_num;
*dp_rate = link_rates[i];
return 0;
}
}
}

return radeon_dp_get_max_link_rate(connector, dpcd);
return -EINVAL;
}

static u8 radeon_dp_encoder_service(struct radeon_device *rdev,
Expand Down Expand Up @@ -491,17 +445,22 @@ void radeon_dp_set_link_config(struct drm_connector *connector,
{
struct radeon_connector *radeon_connector = to_radeon_connector(connector);
struct radeon_connector_atom_dig *dig_connector;
int ret;

if (!radeon_connector->con_priv)
return;
dig_connector = radeon_connector->con_priv;

if ((dig_connector->dp_sink_type == CONNECTOR_OBJECT_ID_DISPLAYPORT) ||
(dig_connector->dp_sink_type == CONNECTOR_OBJECT_ID_eDP)) {
dig_connector->dp_clock =
radeon_dp_get_dp_link_clock(connector, dig_connector->dpcd, mode->clock);
dig_connector->dp_lane_count =
radeon_dp_get_dp_lane_number(connector, dig_connector->dpcd, mode->clock);
ret = radeon_dp_get_dp_link_config(connector, dig_connector->dpcd,
mode->clock,
&dig_connector->dp_lane_count,
&dig_connector->dp_clock);
if (ret) {
dig_connector->dp_clock = 0;
dig_connector->dp_lane_count = 0;
}
}
}

Expand All @@ -510,7 +469,8 @@ int radeon_dp_mode_valid_helper(struct drm_connector *connector,
{
struct radeon_connector *radeon_connector = to_radeon_connector(connector);
struct radeon_connector_atom_dig *dig_connector;
int dp_clock;
unsigned dp_clock, dp_lanes;
int ret;

if ((mode->clock > 340000) &&
(!radeon_connector_is_dp12_capable(connector)))
Expand All @@ -520,8 +480,12 @@ int radeon_dp_mode_valid_helper(struct drm_connector *connector,
return MODE_CLOCK_HIGH;
dig_connector = radeon_connector->con_priv;

dp_clock =
radeon_dp_get_dp_link_clock(connector, dig_connector->dpcd, mode->clock);
ret = radeon_dp_get_dp_link_config(connector, dig_connector->dpcd,
mode->clock,
&dp_lanes,
&dp_clock);
if (ret)
return MODE_CLOCK_HIGH;

if ((dp_clock == 540000) &&
(!radeon_connector_is_dp12_capable(connector)))
Expand Down
12 changes: 9 additions & 3 deletions drivers/gpu/drm/radeon/radeon_dp_mst.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -525,11 +525,17 @@ static bool radeon_mst_mode_fixup(struct drm_encoder *encoder,
drm_mode_set_crtcinfo(adjusted_mode, 0);
{
struct radeon_connector_atom_dig *dig_connector;
int ret;

dig_connector = mst_enc->connector->con_priv;
dig_connector->dp_lane_count = drm_dp_max_lane_count(dig_connector->dpcd);
dig_connector->dp_clock = radeon_dp_get_max_link_rate(&mst_enc->connector->base,
dig_connector->dpcd);
ret = radeon_dp_get_dp_link_config(&mst_enc->connector->base,
dig_connector->dpcd, adjusted_mode->clock,
&dig_connector->dp_lane_count,
&dig_connector->dp_clock);
if (ret) {
dig_connector->dp_lane_count = 0;
dig_connector->dp_clock = 0;
}
DRM_DEBUG_KMS("dig clock %p %d %d\n", dig_connector,
dig_connector->dp_lane_count, dig_connector->dp_clock);
}
Expand Down
6 changes: 4 additions & 2 deletions drivers/gpu/drm/radeon/radeon_mode.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -756,8 +756,10 @@ extern u8 radeon_dp_getsinktype(struct radeon_connector *radeon_connector);
extern bool radeon_dp_getdpcd(struct radeon_connector *radeon_connector);
extern int radeon_dp_get_panel_mode(struct drm_encoder *encoder,
struct drm_connector *connector);
int radeon_dp_get_max_link_rate(struct drm_connector *connector,
const u8 *dpcd);
extern int radeon_dp_get_dp_link_config(struct drm_connector *connector,
const u8 *dpcd,
unsigned pix_clock,
unsigned *dp_lanes, unsigned *dp_rate);
extern void radeon_dp_set_rx_power_state(struct drm_connector *connector,
u8 power_state);
extern void radeon_dp_aux_init(struct radeon_connector *radeon_connector);
Expand Down

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