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

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Date:   Mon, 28 Mar 2022 15:59:24 -0400
From:   Nicolas Dufresne <nicolas.dufresne@...labora.com>
To:     Ezequiel Garcia <ezequiel@...guardiasur.com.ar>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     kernel@...labora.com, linux-media@...r.kernel.org,
        linux-rockchip@...ts.infradead.org, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: [PATCH v1 12/24] media: rkvdec: Stop overclocking the decoder

While this overclock hack seems to works on some implementation (some
ChromeBooks, RockPi4) it is also causing instability on other
implementation (notably LibreComputer Renegade, but saw more reports in
the LibreELEC project, were this is already removed). While performance is
indeed affectied (tested with GStreamer), 4K playback still works as long
as you don't operate in lock step and keep at least 1 frame ahead of time
in the decode queue.

After discussion with ChromeOS members, it would seem that their
implementation indeed synchronously decode each frames, so this hack was
simply compensating for their code being less efficienti. This hack
should in my opinion have stayed downstream and I'm removing it to ensure
stability across all RK3399 variants.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>
---
 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