This patchset fixes several issues in sun4i_tmds_determine_rate that I
discovered while trying to get a projector connected to an Olimex
A20-OLinuXino-LIME using HDMI with a native resolution of 1280x800 and
pixel clock of 83.5 MHz to display at its native resolution.
Changes for v3:
- Improve commit message for unset best_parent
Changes for v2:
- Split into separate patches for each issue
- Add details to commit message for reproducing issue
Jonathan Liu (3):
drm/sun4i: hdmi: Check for unset best_parent in
sun4i_tmds_determine_rate
drm/sun4i: hdmi: Fix incorrect assignment in sun4i_tmds_determine_rate
drm/sun4i: hdmi: Add missing rate halving check in
sun4i_tmds_determine_rate
drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
--
2.15.1
It is possible that if there is no exact rate match and
"rounded = clk_hw_round_rate(parent, ideal)" gives high enough values
(e.g. if rounded is 2 * ideal) that the condition
"abs(rate - rounded / i) < abs(rate - best_parent / best_div)" is never
met and best_parent is never set. This results in req->rate and
req->best_parent_rate being assigned 0.
To avoid this, we set best_parent to the first calculated rate if it is
unset. The sun4i_tmds_calc_divider function already has a similar check.
Fixes: 9c5681011a0c ("drm/sun4i: Add HDMI support")
Signed-off-by: Jonathan Liu <[email protected]>
---
drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
index dc332ea56f6c..4d235e5ea31c 100644
--- a/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
@@ -102,7 +102,7 @@ static int sun4i_tmds_determine_rate(struct clk_hw *hw,
goto out;
}
- if (abs(rate - rounded / i) <
+ if (!best_parent || abs(rate - rounded / i) <
abs(rate - best_parent / best_div)) {
best_parent = rounded;
best_div = i;
--
2.15.1
best_div is set to i which corresponds to rate halving when it should be
set to j which corresponds to the divider.
Fixes: 9c5681011a0c ("drm/sun4i: Add HDMI support")
Signed-off-by: Jonathan Liu <[email protected]>
---
drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
index 4d235e5ea31c..88eeeaf34638 100644
--- a/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
@@ -105,7 +105,7 @@ static int sun4i_tmds_determine_rate(struct clk_hw *hw,
if (!best_parent || abs(rate - rounded / i) <
abs(rate - best_parent / best_div)) {
best_parent = rounded;
- best_div = i;
+ best_div = j;
}
}
}
--
2.15.1
It was only checking the divider when determing the closest match if
it could not match the requested rate exactly.
For a projector connected to an Olimex A20-OLinuXino-LIME using HDMI
with a native resolution of 1280x800 and pixel clock of 83.5 MHz, this
resulted in 1280x800 mode not being available and the following in dmesg
when the kernel is booted with drm.debug=0x3e:
[drm:drm_mode_debug_printmodeline] Modeline 37:"1280x800" 60 83500 1280 1352 1480 1680 800 810 816 831 0x48 0x5
[drm:drm_mode_prune_invalid] Not using 1280x800 mode: NOCLOCK
Fixes: 9c5681011a0c ("drm/sun4i: Add HDMI support")
Signed-off-by: Jonathan Liu <[email protected]>
---
drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
index 88eeeaf34638..3ecffa52c814 100644
--- a/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
@@ -102,9 +102,12 @@ static int sun4i_tmds_determine_rate(struct clk_hw *hw,
goto out;
}
- if (!best_parent || abs(rate - rounded / i) <
- abs(rate - best_parent / best_div)) {
+ if (!best_parent ||
+ abs(rate - rounded / i / j) <
+ abs(rate - best_parent / best_half /
+ best_div)) {
best_parent = rounded;
+ best_half = i;
best_div = j;
}
}
--
2.15.1
On Tue, Jan 09, 2018 at 01:03:20PM +1100, Jonathan Liu wrote:
> This patchset fixes several issues in sun4i_tmds_determine_rate that I
> discovered while trying to get a projector connected to an Olimex
> A20-OLinuXino-LIME using HDMI with a native resolution of 1280x800 and
> pixel clock of 83.5 MHz to display at its native resolution.
Queued all three patches as fixes, thanks!
maxime
--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com