Re: [PATCH] ACPI: scan: Honor _DEP for Intel CVS devices

[Thorsten Leemhuis]

On 9/12/26 18:50, Thorsten Leemhuis wrote:
> On 6/1/26 21:40, Miguel Vadillo wrote:
>> CVS (Computer Vision Sensing) is an ACPI-enumerated device that sits
>> inline in the CSI-2 path between the camera sensor and Intel IPU.
>> On platforms where CVS is present, the camera sensor's ACPI node
>> declares a _DEP dependency on the CVS device.
>>
>> The CVS driver must be fully initialized before camera sensor drivers
>> probe, because CVS controls the CSI-2 link ownership handshake (via
>> GPIO REQ/RESP), the MIPI/CSI-2 lane configuration, and the camera
>> power domain. Without CVS ready, the sensor driver can bind but the
>> CSI-2 stream will not function correctly.
>>
>> The CVS driver calls acpi_dev_clear_dependencies() at the end of its
>> probe() to unblock waiting consumers once it is ready.
>>
>> Move the CVS HIDs from acpi_ignore_dep_ids[] to acpi_honor_dep_ids[]
>> so that camera sensor enumeration is deferred until the CVS driver has
>> finished probing, matching the behavior already in place for IVSC.
> 
> TWIMC, there is a bug report where one or two people claim that this
> change caused a regression; the report is quite verbose (guess LLM
> assisted) and hard to grasp for me as outsider; requests for
> clarifications from my side were not really fruitful. Not sure what to
> make of this, but I thought I'd let you know; for details see:
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=221988

For completeness, a report that is more straight forward to read (at
least for me) was now posted here:
https://lore.kernel.org/all/20260912185836.309071-1-manuel.knitza@xxxxxxxxxxxxxx/

Cia, Thorsten

>> Signed-off-by: Miguel Vadillo <miguel.vadillo@xxxxxxxxx>
>> ---
>> Note: this patch has a functional dependency on the CVS driver and its
>> IPU bridge support, which are queued in media-next for v7.2. Without
>> those drivers, no code will call acpi_dev_clear_dependencies() for the
>> CVS HIDs and camera sensors will remain deferred indefinitely.
>>
>> The CVS driver series (v5) can be found at:
>>   https://lore.kernel.org/linux-media/20260527170531.383871-1-miguel.vadillo@xxxxxxxxx/
>>
>>  drivers/acpi/scan.c | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
>> index 530547cda8b2..1463eb3a4f6e 100644
>> --- a/drivers/acpi/scan.c
>> +++ b/drivers/acpi/scan.c
>> @@ -848,8 +848,6 @@ static bool acpi_info_matches_ids(struct acpi_device_info *info,
>>  static const char * const acpi_ignore_dep_ids[] = {
>>  	"PNP0D80", /* Windows-compatible System Power Management Controller */
>>  	"INT33BD", /* Intel Baytrail Mailbox Device */
>> -	"INTC10DE", /* Intel CVS LNL */
>> -	"INTC10E0", /* Intel CVS ARL */
>>  	"LATT2021", /* Lattice FW Update Client Driver */
>>  	NULL
>>  };
>> @@ -861,6 +859,9 @@ static const char * const acpi_honor_dep_ids[] = {
>>  	"INTC1095", /* IVSC (ADL) driver must be loaded to allow i2c access to camera sensors */
>>  	"INTC100A", /* IVSC (RPL) driver must be loaded to allow i2c access to camera sensors */
>>  	"INTC10CF", /* IVSC (MTL) driver must be loaded to allow i2c access to camera sensors */
>> +	"INTC10DE", /* CVS (LNL) driver must be loaded to allow camera streaming */
>> +	"INTC10E0", /* CVS (ARL) driver must be loaded to allow camera streaming */
>> +	"INTC10E1", /* CVS (PTL) driver must be loaded to allow camera streaming */
>>  	"RSCV0001", /* RISC-V PLIC */
>>  	"RSCV0002", /* RISC-V APLIC */
>>  	"RSCV0005", /* RISC-V SBI MPXY MBOX */
> 
>