linux-kernel - Re: [PATCH v3] media: iris: Refine internal buffer reconfiguration logic for resolution change

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Message-ID: <220c9fe4-00b4-3b42-0e80-8730a6388bde@oss.qualcomm.com>
Date: Mon, 10 Nov 2025 14:31:20 +0530
From: Dikshita Agarwal <dikshita.agarwal@....qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Vikash Garodia <vikash.garodia@....qualcomm.com>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Bryan O'Donoghue <bod@...nel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil@...nel.org>,
        Stefan Schmidt <stefan.schmidt@...aro.org>,
        linux-media@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Val Packett <val@...kett.cool>
Subject: Re: [PATCH v3] media: iris: Refine internal buffer reconfiguration
 logic for resolution change



On 11/10/2025 2:46 AM, Dmitry Baryshkov wrote:
> On Wed, Nov 05, 2025 at 11:17:37AM +0530, Dikshita Agarwal wrote:
>> Improve the condition used to determine when input internal buffers need
>> to be reconfigured during streamon on the capture port. Previously, the
>> check relied on the INPUT_PAUSE sub-state, which was also being set
>> during seek operations. This led to input buffers being queued multiple
>> times to the firmware, causing session errors due to duplicate buffer
>> submissions.
>>
>> This change introduces a more accurate check using the FIRST_IPSC and
>> DRC sub-states to ensure that input buffer reconfiguration is triggered
>> only during resolution change scenarios, such as streamoff/on on the
>> capture port. This avoids duplicate buffer queuing during seek
>> operations.
>>
>> Fixes: c1f8b2cc72ec ("media: iris: handle streamoff/on from client in dynamic resolution change")
>> Cc: stable@...r.kernel.org
>> Reported-by: Val Packett <val@...kett.cool>
>> Closes: https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/4700
>> Signed-off-by: Dikshita Agarwal <dikshita.agarwal@....qualcomm.com>
>> ---
>> Changes in v3:
>> - Fixed the compilation issue
>> - Added stable@...r.kernel.org in Cc
>> - Link to v2: https://lore.kernel.org/r/20251104-iris-seek-fix-v2-1-c9dace39b43d@oss.qualcomm.com
>>
>> Changes in v2:
>> - Removed spurious space and addressed other comments (Nicolas)
>> - Remove the unnecessary initializations (Self) 
>> - Link to v1: https://lore.kernel.org/r/20251103-iris-seek-fix-v1-1-6db5f5e17722@oss.qualcomm.com
>> ---
>>  drivers/media/platform/qcom/iris/iris_common.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/media/platform/qcom/iris/iris_common.c b/drivers/media/platform/qcom/iris/iris_common.c
>> index 9fc663bdaf3fc989fe1273b4d4280a87f68de85d..7f1c7fe144f707accc2e3da65ce37cd6d9dfeaff 100644
>> --- a/drivers/media/platform/qcom/iris/iris_common.c
>> +++ b/drivers/media/platform/qcom/iris/iris_common.c
>> @@ -91,12 +91,14 @@ int iris_process_streamon_input(struct iris_inst *inst)
>>  int iris_process_streamon_output(struct iris_inst *inst)
>>  {
>>  	const struct iris_hfi_command_ops *hfi_ops = inst->core->hfi_ops;
>> -	bool drain_active = false, drc_active = false;
>>  	enum iris_inst_sub_state clear_sub_state = 0;
>> +	bool drain_active, drc_active, first_ipsc;
>>  	int ret = 0;
>>  
>>  	iris_scale_power(inst);
>>  
>> +	first_ipsc = inst->sub_state & IRIS_INST_SUB_FIRST_IPSC;
>> +
>>  	drain_active = inst->sub_state & IRIS_INST_SUB_DRAIN &&
>>  		inst->sub_state & IRIS_INST_SUB_DRAIN_LAST;
>>  
>> @@ -108,7 +110,8 @@ int iris_process_streamon_output(struct iris_inst *inst)
>>  	else if (drain_active)
>>  		clear_sub_state = IRIS_INST_SUB_DRAIN | IRIS_INST_SUB_DRAIN_LAST;
>>  
>> -	if (inst->domain == DECODER && inst->sub_state & IRIS_INST_SUB_INPUT_PAUSE) {
>> +	/* Input internal buffer reconfiguration required in case of resolution change */
>> +	if (first_ipsc || drc_active) {
>>  		ret = iris_alloc_and_queue_input_int_bufs(inst);
>>  		if (ret)
>>  			return ret;
> 
> I will repeat my (unanswered) question from v2:
> 
> After this line comes manual writing of STAGE and PIPE. Could you please
> point out where is the driver updating the resolution in the firmware?
> And if it does, why do we need to write STAGE and PIPE again?

Sorry for late reply,

During streamon on the output port, the driver sets the resolution in the
firmware. However, during Dynamic Resolution Change (DRC), the resolution
update originates from the firmware and is communicated to the driver. As a
result, the driver does not proactively update the resolution in the
firmware during DRC.

STAGE parameter depends on the resolution, the driver must update the
firmware with the new STAGE value after a resolution change to ensure
proper operation.

On the other hand, the PIPE value is independent of resolution. It is
typically updated to 1 for interlaced content, which is identified during
the sequence change. Currently, the Iris driver does not support interlaced
content, so updating the PIPE value during DRC handling is redundant.
However, this update is harmless and will be necessary once interlace
support is added in the future.

Thanks,
Dikshita
>