Hi Mathieu,
On 3/17/20 1:05 PM, Mathieu Poirier wrote:
> Hi Suman,
>
> On Thu, Mar 05, 2020 at 04:41:08PM -0600, Suman Anna wrote:
>> The commit 086d08725d34 ("remoteproc: create vdev subdevice with specific
>> dma memory pool") has introduced a new vdev subdevice for each vdev
>> declared in the firmware resource table and made it as the parent for the
>> created virtio rpmsg devices instead of the previous remoteproc device.
>> This changed the overall parenting hierarchy for the rpmsg devices, which
>> were children of virtio devices, and does not allow the corresponding
>> rpmsg drivers to retrieve the parent rproc device through the
>> rproc_get_by_child() API.
>>
>> Fix this by restoring the remoteproc device as the parent. The new vdev
>> subdevice can continue to inherit the DMA attributes from the remoteproc's
>> parent device (actual platform device).
>>
>> Fixes: 086d08725d34 ("remoteproc: create vdev subdevice with specific dma memory pool")
>> Signed-off-by: Suman Anna <s-anna@xxxxxx>
>> ---
>> drivers/remoteproc/remoteproc_core.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
>> index 097f33e4f1f3..ba18f32bd0c4 100644
>> --- a/drivers/remoteproc/remoteproc_core.c
>> +++ b/drivers/remoteproc/remoteproc_core.c
>> @@ -510,7 +510,7 @@ static int rproc_handle_vdev(struct rproc *rproc, struct fw_rsc_vdev *rsc,
>>
>> /* Initialise vdev subdevice */
>> snprintf(name, sizeof(name), "vdev%dbuffer", rvdev->index);
>> - rvdev->dev.parent = rproc->dev.parent;
>> + rvdev->dev.parent = &rproc->dev;
>
> I can see how it would not be possible to retrieve the parent rproc device since
> rvdev->dev.parent was set to be platform device...
>
> I wonder how the original change didn't blow up sysmon_probe() and potentially
> other out-of-tree users of rproc_get_by_child().
QCOM code uses SMD transport, and not virtio_rpmsg transport, and the
parent-child relationship is direct rproc subdevices which are added in
their platform drivers directly. This affects only virtio-rpmsg clients.
Please see qcom_add_smd_subdev().
It would be nice to have
> someone from the QCOM team test your patch.
>
>> rvdev->dev.dma_pfn_offset = rproc->dev.parent->dma_pfn_offset;
>> rvdev->dev.release = rproc_rvdev_release;
>> dev_set_name(&rvdev->dev, "%s#%s", dev_name(rvdev->dev.parent), name);
>
> Be mindful there might be fallouts from applying this patch since it does change
> the location of the vdev under /sys/device/platform/ .
>
> Reviewed-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Thanks for the review.
regards
Suman
