linux-kernel - Re: [PATCH v1 12/24] media: rkvdec: Stop overclocking the decoder

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Date:   Tue, 29 Mar 2022 17:15:33 +0200
From:   Sebastian Fricke <sebastian.fricke@...labora.com>
To:     Nicolas Dufresne <nicolas.dufresne@...labora.com>
Cc:     Ezequiel Garcia <ezequiel@...guardiasur.com.ar>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        kernel@...labora.com, linux-media@...r.kernel.org,
        linux-rockchip@...ts.infradead.org, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 12/24] media: rkvdec: Stop overclocking the decoder

Hey Nicolas,

On 28.03.2022 15:59, Nicolas Dufresne wrote:
>While this overclock hack seems to works on some implementation (some

s/implementation/implementations/

>ChromeBooks, RockPi4) it is also causing instability on other

s/causing/causes/

>implementation (notably LibreComputer Renegade, but saw more reports in

s/implementation/implementations/

s/but saw more reports/but there were more reports/

>the LibreELEC project, were this is already removed). While performance is

s/were this is/where this is/

>indeed affectied (tested with GStreamer), 4K playback still works as long

s/affectied/affected/

>as you don't operate in lock step and keep at least 1 frame ahead of time

s/lock step/lock step mode/

>in the decode queue.
>
>After discussion with ChromeOS members, it would seem that their
>implementation indeed synchronously decode each frames, so this hack was

s/decode each frames/decodes each frame/

>simply compensating for their code being less efficienti. This hack

s/efficienti/efficient/

>should in my opinion have stayed downstream and I'm removing it to ensure

s/This hack should in my opinion have stayed downstream/
   In my opinion, this hack should not have been included upstream/

>stability across all RK3399 variants.
>
>Signed-off-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>
Reviewed-by: Sebastian Fricke <sebastian.fricke@...labora.com>

Greetings,
Sebastian

>---
> drivers/staging/media/rkvdec/rkvdec.c | 6 ------
> 1 file changed, 6 deletions(-)
>
>diff --git a/drivers/staging/media/rkvdec/rkvdec.c b/drivers/staging/media/rkvdec/rkvdec.c
>index c0cf3488f970..2df8cf4883e2 100644
>--- a/drivers/staging/media/rkvdec/rkvdec.c
>+++ b/drivers/staging/media/rkvdec/rkvdec.c
>@@ -1027,12 +1027,6 @@ static int rkvdec_probe(struct platform_device *pdev)
> 	if (ret)
> 		return ret;
>
>-	/*
>-	 * Bump ACLK to max. possible freq. (500 MHz) to improve performance
>-	 * When 4k video playback.
>-	 */
>-	clk_set_rate(rkvdec->clocks[0].clk, 500 * 1000 * 1000);
>-
> 	rkvdec->regs = devm_platform_ioremap_resource(pdev, 0);
> 	if (IS_ERR(rkvdec->regs))
> 		return PTR_ERR(rkvdec->regs);
>-- 
>2.34.1
>