linux-kernel - Re: [PATCH] media: aspeed: Fix dram hang at res-change

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Message-ID: <120162b9.3256.19aca13d4e0.Coremail.wangmin@phytium.com.cn>
Date: Fri, 28 Nov 2025 18:48:08 +0800 (GMT+08:00)
From: 王敏 <wangmin@...tium.com.cn>
To: "Jammy Huang" <jammy_huang@...eedtech.com>
Cc: "Eddie James" <eajames@...ux.ibm.com>,
	"Mauro Carvalho Chehab" <mchehab@...nel.org>,
	"Joel Stanley" <joel@....id.au>,
	"Andrew Jeffery" <andrew@...econstruct.com.au>,
	"Philipp Zabel" <p.zabel@...gutronix.de>,
	linux-media@...r.kernel.org, openbmc@...ts.ozlabs.org,
	linux-arm-kernel@...ts.infradead.org, linux-aspeed@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org,
	舒奕棋 <shuyiqi@...tium.com.cn>
Subject: Re: [PATCH] media: aspeed: Fix dram hang at res-change




> -----原始邮件-----
> 发件人: "Jammy Huang" <jammy_huang@...eedtech.com>
> 发送时间:2025-11-24 11:05:14 (星期一)
> 收件人: "Eddie James" <eajames@...ux.ibm.com>, "Mauro Carvalho Chehab" <mchehab@...nel.org>, "Joel Stanley" <joel@....id.au>, "Andrew Jeffery" <andrew@...econstruct.com.au>, "Philipp Zabel" <p.zabel@...gutronix.de>
> 抄送: linux-media@...r.kernel.org, openbmc@...ts.ozlabs.org, linux-arm-kernel@...ts.infradead.org, linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org, "Jammy Huang" <jammy_huang@...eedtech.com>
> 主题: [PATCH] media: aspeed: Fix dram hang at res-change
> 
> Dram hang could happen in the steps below:
> 1. start capture/compression
> 2. out-of-lock watchdog raise irq because of res-change.
> 3. aspeed_video_irq_res_change do clk-off
> 
> At step3, capture/compression could be not accomplished yet. If clk-off
> in the middle of video operation, dram controller could hang at ast2500.
> 
> Use reset rather than clk-off/on to avoid this problem.
> 
> Signed-off-by: Jammy Huang <jammy_huang@...eedtech.com>
> ---
> On Aspeed KVM testing, we found it could lead to dram-hang if
> res-change. Although the issue rarely happens, the impact is serious.

Capturing and compressing the video stream takes longer than the video engine’s idle period. 
If this is not the intended behavior, please increase the frame rate. This makes resolution 
switches more prone to happen when the video engine is working. However, according to your 
email, this issue rarely occurs. Is there a similar issue on the AST2600 SoC?

> 
> To avoid this issue, we use reset only rathar than clk-off/on in
> res-change to avoid this issue.
> ---
>  drivers/media/platform/aspeed/aspeed-video.c | 22 +++++++++++++++++++---
>  1 file changed, 19 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/platform/aspeed/aspeed-video.c b/drivers/media/platform/aspeed/aspeed-video.c
> index b83e432452..41cb96f601 100644
> --- a/drivers/media/platform/aspeed/aspeed-video.c
> +++ b/drivers/media/platform/aspeed/aspeed-video.c
> @@ -26,6 +26,7 @@
>  #include <linux/workqueue.h>
>  #include <linux/debugfs.h>
>  #include <linux/ktime.h>
> +#include <linux/reset.h>
>  #include <linux/regmap.h>
>  #include <linux/mfd/syscon.h>
>  #include <media/v4l2-ctrls.h>
> @@ -310,6 +311,7 @@ struct aspeed_video {
>  	void __iomem *base;
>  	struct clk *eclk;
>  	struct clk *vclk;
> +	struct reset_control *reset;
>  
>  	struct device *dev;
>  	struct v4l2_ctrl_handler ctrl_handler;
> @@ -720,6 +722,13 @@ static void aspeed_video_on(struct aspeed_video *video)
>  	set_bit(VIDEO_CLOCKS_ON, &video->flags);
>  }
>  
> +static void aspeed_video_reset(struct aspeed_video *v)
> +{
> +	reset_control_assert(v->reset);
> +	usleep_range(100, 150);
> +	reset_control_deassert(v->reset);
> +}
> +
>  static void aspeed_video_bufs_done(struct aspeed_video *video,
>  				   enum vb2_buffer_state state)
>  {
> @@ -742,7 +751,9 @@ static void aspeed_video_irq_res_change(struct aspeed_video *video, ulong delay)
>  
>  	video->v4l2_input_status = V4L2_IN_ST_NO_SIGNAL;
>  
> -	aspeed_video_off(video);
> +	aspeed_video_write(video, VE_INTERRUPT_CTRL, 0);
> +	aspeed_video_write(video, VE_INTERRUPT_STATUS, 0xffffffff);
> +	aspeed_video_reset(video);
>  	aspeed_video_bufs_done(video, VB2_BUF_STATE_ERROR);
>  
>  	schedule_delayed_work(&video->res_work, delay);
> @@ -1984,8 +1995,7 @@ static void aspeed_video_stop_streaming(struct vb2_queue *q)
>  		 * Need to force stop any DMA and try and get HW into a good
>  		 * state for future calls to start streaming again.
>  		 */
> -		aspeed_video_off(video);
> -		aspeed_video_on(video);
> +		aspeed_video_reset(video);
>  
>  		aspeed_video_init_regs(video);
>  
> @@ -2230,6 +2240,12 @@ static int aspeed_video_init(struct aspeed_video *video)
>  	}
>  	dev_info(video->dev, "irq %d\n", irq);
>  
> +	video->reset = devm_reset_control_get(dev, NULL);
> +	if (IS_ERR(video->reset)) {
> +		dev_err(dev, "Unable to get reset\n");
> +		return PTR_ERR(video->reset);
> +	}
> +
>  	video->eclk = devm_clk_get(dev, "eclk");
>  	if (IS_ERR(video->eclk)) {
>  		dev_err(dev, "Unable to get ECLK\n");
> 
> ---
> base-commit: ac3fd01e4c1efce8f2c054cdeb2ddd2fc0fb150d
> change-id: 20251124-video_dram_reset-c531f6ba573f
> 
> Best regards,
> -- 
> Jammy Huang <jammy_huang@...eedtech.com>
>




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