Re: [PATCH 1/4] soc: qcom: aoss: Move length requirements from caller

[Chris Lew]

On 7/31/2023 4:10 PM, Bjorn Andersson wrote:
> On Mon, Jul 31, 2023 at 02:29:44PM -0700, Chris Lew wrote:
> > On 7/30/2023 9:10 PM, Bjorn Andersson wrote:
> > > diff --git a/drivers/soc/qcom/qcom_aoss.c b/drivers/soc/qcom/qcom_aoss.c
> > >    	/* The message RAM only implements 32-bit accesses */
> > >    	__iowrite32_copy(qmp->msgram + qmp->offset + sizeof(u32),
> > > -			 data, len / sizeof(u32));
> > > -	writel(len, qmp->msgram + qmp->offset);
> > > +			 buf, sizeof(buf) / sizeof(u32));
> > > +	writel(sizeof(buf), qmp->msgram + qmp->offset);
> >
> > Looks like we are telling the firmware the packet size will always be
> > QMP_MSG_LEN?
> >
> > This should be ok but might be a problem when debugging. The AOSS firmware
> > only logs size of the message instead of the full string because of memory
> > constraints.
>
> Until now ipa_power_retention() has been passing 36 here, everyone else
> 64, so it is ok.
>
> > We would normally match the firmware and host logs based on size, but won't
> > be able to differentiate this way with a fixed size.
>
> I don't mind us changing it to ALIGN(len, 4), but as that would change
> the current behavior I'd like to do so in a subsequent patch.
>
> Speaking of behavior, is 64 the max message size? We inherited the 64
> from the initial downstream implementation, but qmp->size is quite a bit
> bigger.

The max message size the firmware can handle is 0x64, so 100 bytes, but 
I haven't seen any messages go above 64 bytes.

> Regards,
> Bjorn