This is a note to let you know that I've just added the patch titled
gpu: ipu-v3: Fix dev_dbg frequency output
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
gpu-ipu-v3-fix-dev_dbg-frequency-output.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit e7db1d6f2839ef3607277be3e7db675e5d001d18
Author: Leo Ruan <tingquan.ruan@xxxxxxxxxxxx>
Date: Mon Feb 7 16:14:11 2022 +0100
gpu: ipu-v3: Fix dev_dbg frequency output
[ Upstream commit 070a88fd4a03f921b73a2059e97d55faaa447dab ]
This commit corrects the printing of the IPU clock error percentage if
it is between -0.1% to -0.9%. For example, if the pixel clock requested
is 27.2 MHz but only 27.0 MHz can be achieved the deviation is -0.8%.
But the fixed point math had a flaw and calculated error of 0.2%.
Before:
Clocks: IPU 270000000Hz DI 24716667Hz Needed 27200000Hz
IPU clock can give 27000000 with divider 10, error 0.2%
Want 27200000Hz IPU 270000000Hz DI 24716667Hz using IPU, 27000000Hz
After:
Clocks: IPU 270000000Hz DI 24716667Hz Needed 27200000Hz
IPU clock can give 27000000 with divider 10, error -0.8%
Want 27200000Hz IPU 270000000Hz DI 24716667Hz using IPU, 27000000Hz
Signed-off-by: Leo Ruan <tingquan.ruan@xxxxxxxxxxxx>
Signed-off-by: Mark Jonas <mark.jonas@xxxxxxxxxxxx>
Reviewed-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
Signed-off-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220207151411.5009-1-mark.jonas@xxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/ipu-v3/ipu-di.c b/drivers/gpu/ipu-v3/ipu-di.c
index a8d87ddd8a17..dc0511b22600 100644
--- a/drivers/gpu/ipu-v3/ipu-di.c
+++ b/drivers/gpu/ipu-v3/ipu-di.c
@@ -460,8 +460,9 @@ static void ipu_di_config_clock(struct ipu_di *di,
error = rate / (sig->mode.pixelclock / 1000);
- dev_dbg(di->ipu->dev, " IPU clock can give %lu with divider %u, error %d.%u%%\n",
- rate, div, (signed)(error - 1000) / 10, error % 10);
+ dev_dbg(di->ipu->dev, " IPU clock can give %lu with divider %u, error %c%d.%d%%\n",
+ rate, div, error < 1000 ? '-' : '+',
+ abs(error - 1000) / 10, abs(error - 1000) % 10);
/* Allow a 1% error */
if (error < 1010 && error >= 990) {
