hello
On 10/23/24 17:32, Mathieu Poirier wrote:
> Hello Daniel,
>
> On Fri, Oct 18, 2024 at 02:09:29PM +0300, Daniel Baluta wrote:
>> Currently we generate notifyids in the linux kernel and override
>> those found in rsc_table.
>>
>> This doesn't play well with users expecting to use the exact ids
>> from rsc_table.
>>
>> So, use predefined notifyids found in rsc_table if any. Otherwise,
>> let Linux generate the ids as before.
>>
>> Keypoint is we also define an invalid notifid as 0xFFFFFFFFU. This
>> should be placed as notifids if users want Linux to generate the ids.
>>
>> Signed-off-by: Alexandru Lastur <alexandru.lastur@xxxxxxx>
>> Signed-off-by: Daniel Baluta <daniel.baluta@xxxxxxx>
>> ---
>> drivers/remoteproc/remoteproc_core.c | 14 ++++++++++++--
>> include/linux/remoteproc.h | 1 +
>> 2 files changed, 13 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
>> index f276956f2c5c..9f00fe16da38 100644
>> --- a/drivers/remoteproc/remoteproc_core.c
>> +++ b/drivers/remoteproc/remoteproc_core.c
>> @@ -332,6 +332,7 @@ int rproc_alloc_vring(struct rproc_vdev *rvdev, int i)
>> int ret, notifyid;
>> struct rproc_mem_entry *mem;
>> size_t size;
>> + int start, end;
>>
>> /* actual size of vring (in bytes) */
>> size = PAGE_ALIGN(vring_size(rvring->num, rvring->align));
>> @@ -363,9 +364,18 @@ int rproc_alloc_vring(struct rproc_vdev *rvdev, int i)
>> /*
>> * Assign an rproc-wide unique index for this vring
>> * TODO: assign a notifyid for rvdev updates as well
>> - * TODO: support predefined notifyids (via resource table)
>> */
>> - ret = idr_alloc(&rproc->notifyids, rvring, 0, 0, GFP_KERNEL);
>> +
>> + start = 0;
>> + end = 0;
>> +
>> + /* use id if specified in rsc table */
>> + if (rsc->vring[i].notifyid != RSC_INVALID_NOTIFYID) {
>> + start = rsc->vring[i].notifyid;
>> + end = start + 1;
>> + }
>
> This will likely introduce a backward compatibility issue where anyone that
> has more than one vring and set their notifyids to anything else than 0xFFFFFFFF
> in the resource table will see a boot failure.
>
> A while back the openAMP group started discussions on using the configuration
> space of a virtio device to enhance device discovery, with exactly this kind of
> use case in mind. I think it is the only way to move forward with this
> feature, though it is a big job that requires a lot of community interactions.
>
FYI a PR exists in OpenAMP to use this configuration space to customize the
size of the buffers [2].
This probably means we need something scalable for the configuration space.
I guess your objective is to match the vring ID with the mailbox channel ID, right?
We have a similar issue with the STM32MP1/2. It is hard-coded in the stm32_rproc
driver[1], which is far from perfect because it is not simple to add a new vdev
instance.
I would have two other alternatives to highlight
- An alternative could be to have a vendor resource in the resource table and
use rproc_handle_rsc operations. This resource would define the match between the
vrings IDs and the mailbox IDs.
However, if several vendors are facing the same issue, perhaps better to find a
generic solution.
- another alternative already discussed several times in openAMP group would be
to define a new version of the resource table.
[1]https://elixir.bootlin.com/linux/v6.11/source/drivers/remoteproc/stm32_rproc.c#L328
[2] https://github.com/OpenAMP/open-amp/pull/155
Regards
Arnaud
> Regards,
> Mathieu
>
>> +
>> + ret = idr_alloc(&rproc->notifyids, rvring, start, end, GFP_KERNEL);
>> if (ret < 0) {
>> dev_err(dev, "idr_alloc failed: %d\n", ret);
>> return ret;
>> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
>> index b4795698d8c2..98c3e181086e 100644
>> --- a/include/linux/remoteproc.h
>> +++ b/include/linux/remoteproc.h
>> @@ -238,6 +238,7 @@ struct fw_rsc_trace {
>> u8 name[32];
>> } __packed;
>>
>> +#define RSC_INVALID_NOTIFYID 0xFFFFFFFFU
>> /**
>> * struct fw_rsc_vdev_vring - vring descriptor entry
>> * @da: device address
>> --
>> 2.43.0
>>
>
