From: Leo Ruan <tingquan.ruan@xxxxxxxxxxxx> [ 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> --- drivers/gpu/ipu-v3/ipu-di.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/ipu-v3/ipu-di.c b/drivers/gpu/ipu-v3/ipu-di.c index b4a31d506fcc..74eca68891ad 100644 --- a/drivers/gpu/ipu-v3/ipu-di.c +++ b/drivers/gpu/ipu-v3/ipu-di.c @@ -451,8 +451,9 @@ 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) { -- 2.35.1
