Hi Jammy,
On 05/11/2021 02:27, Jammy Huang wrote:
> Hi Jae,
>
> OK, I found it.
> Thanks for your help.
So just so I understand this correctly: this patch can be dropped, right?
Regards,
Hans
>
> Regards,
> Jammy Huang
>
> Tel: 886-3-575-1185 ext.8630
>
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> -----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");
>>
