Hi Cezary,
On Sat, Aug 17, 2019 at 6:22 PM Cezary Rojewski
<cezary.rojewski@xxxxxxxxx> wrote:
>
> On 2019-08-15 17:44, Pierre-Louis Bossart wrote:
> > From: Daniel Baluta <daniel.baluta@xxxxxxx>
> >
> > Add support for the audio DSP hardware found on NXP i.MX8 platform.
> >
> > Signed-off-by: Daniel Baluta <daniel.baluta@xxxxxxx>
> > Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
> > +static void imx8_get_reply(struct snd_sof_dev *sdev)
> > +{
> > + struct snd_sof_ipc_msg *msg = sdev->msg;
> > + struct sof_ipc_reply reply;
> > + int ret = 0;
> > +
> > + if (!msg) {
> > + dev_warn(sdev->dev, "unexpected ipc interrupt\n");
> > + return;
> > + }
> > +
> > + /* get reply */
> > + sof_mailbox_read(sdev, sdev->host_box.offset, &reply, sizeof(reply));
> > +
> > + if (reply.error < 0) {
> > + memcpy(msg->reply_data, &reply, sizeof(reply));
> > + ret = reply.error;
> > + } else {
> > + /* reply has correct size? */
> > + if (reply.hdr.size != msg->reply_size) {
> > + dev_err(sdev->dev, "error: reply expected %zu got %u bytes\n",
> > + msg->reply_size, reply.hdr.size);
> > + ret = -EINVAL;
> > + }
> > +
> > + /* read the message */
> > + if (msg->reply_size > 0)
> > + sof_mailbox_read(sdev, sdev->host_box.offset,
> > + msg->reply_data, msg->reply_size);
> > + }
> > +
> > + msg->reply_error = ret;
> > +}
>
> Assuming reply.hdr.size is coming from HW IPC regs, msg object is
> representing application side - SW, kernel. If so, is msg->reply_size
> value an estimated size (which can be overestimated since exact size may
> be unknown by the host) -or- the exact size of incoming IPC reply?
>
I would say msg->reply_size is the exact size of incoming IPC. At least for this
example:
Look at sound/soc/sof/pcm.c
sof_pcm_trigger
-> sof_ipc_tx_message(..,..,&reply, sizeof(reply))
msg->reply_size = sizeof(reply).
On the firmware side:
https://github.com/thesofproject/sof/blob/master/src/ipc/handler.c#L912
reply.rhdr.hdr.size = sizeof(reply);
> The estimated-case is usually permissive as long as assumed size is >=
> reply.hdr.size - dev_err needed. In the exact-case, it should be viewed
> as a requirement. If such "requirement" fails, is it valid to read
> mailbox regardless? Is this to extract some error-debug payload sent by FW?
>
> Just curious, please feel free to correct me here, Pierre.
If you think an improvement can be done, please send a patch :).
thanks,
Daniel.
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