Hi Jae,
OK, I found it.
Thanks for your help.
Regards,
Jammy Huang
Tel: 886-3-575-1185 ext.8630
************* Email Confidentiality Notice ********************
DISCLAIMER:
This message (and any attachments) may contain legally privileged and/or other confidential information. If you have received it in error, please notify the sender by reply e-mail and immediately delete the e-mail and any attachments without copying or disclosing the contents. Thank you.
-----Original Message-----
From: Jae Hyun Yoo <jae.hyun.yoo@xxxxxxxxxxxxxxx>
Sent: Thursday, November 4, 2021 11:54 PM
To: Jammy Huang <jammy_huang@xxxxxxxxxxxxxx>; eajames@xxxxxxxxxxxxx; mchehab@xxxxxxxxxx; joel@xxxxxxxxx; andrew@xxxxxxxx; linux-media@xxxxxxxxxxxxxxx; openbmc@xxxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-aspeed@xxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
Subject: Re: [PATCH] media: aspeed: use reset to replace clk off/on
Hi Jammy,
On 11/2/2021 10:43 PM, Jammy Huang wrote:
> reset should be more proper than clk off/on to bring HW back to good
> state.
>
> Signed-off-by: Jammy Huang <jammy_huang@xxxxxxxxxxxxxx>
> ---
> drivers/media/platform/aspeed-video.c | 22 +++++++++++++++++++---
> 1 file changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/platform/aspeed-video.c
> b/drivers/media/platform/aspeed-video.c
> index fea5e4d0927e..10d182139809 100644
> --- a/drivers/media/platform/aspeed-video.c
> +++ b/drivers/media/platform/aspeed-video.c
> @@ -23,6 +23,7 @@
> #include <linux/workqueue.h>
> #include <linux/debugfs.h>
> #include <linux/ktime.h>
> +#include <linux/reset.h>
> #include <media/v4l2-ctrls.h>
> #include <media/v4l2-dev.h>
> #include <media/v4l2-device.h>
> @@ -220,6 +221,7 @@ 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; @@ -554,6 +556,13 @@ 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);
> + udelay(100);
> + reset_control_deassert(v->reset);
> +}
> +
> static void aspeed_video_bufs_done(struct aspeed_video *video,
> enum vb2_buffer_state state)
> {
> @@ -574,7 +583,9 @@ static void aspeed_video_irq_res_change(struct aspeed_video *video, ulong delay)
> set_bit(VIDEO_RES_CHANGE, &video->flags);
> clear_bit(VIDEO_FRAME_INPRG, &video->flags);
>
> - 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); @@ -1507,8 +1518,7
> @@ 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);
You can find the ECLK configuration in 'clk-aspeed.c' or in 'clk-ast2600.c' that it's coupled with the video engine reset (SCU04[6] for AST2500 / SCU040[6] for AST2600). It means that if we call
clk_disable() and clk_enable() through aspeed_video_off() and aspeed_video_on(), the video engine reset will be implicitly asserted and de-asserted by the clock driver so the reset mechanism is already in the existing code.
Thanks,
Jae
> aspeed_video_init_regs(video);
>
> @@ -1715,6 +1725,12 @@ static int aspeed_video_init(struct aspeed_video *video)
> return rc;
> }
>
> + 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");
>
