AW: [PATCH] gpu: ipu-v3: Fix dev_dbg frequency output

From: Jonas Mark (BT-FIR/ENG1-Grb)
Date: Mon Feb 14 2022 - 11:44:54 EST


Hi,

> From: Leo Ruan <tingquan.ruan@xxxxxxxxxxxx>
>
> 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>
> ---
> 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) {

Is there anything I can do to help getting this patch mainline?

Cheers,
Mark

Mark Jonas

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