[Freedreno] [PATCH 10/12] firmware: qcom_scm: Add qcom_scm_gpu_zap_resume()

[Jordan Crouse]

On Sat, Jan 14, 2017 at 11:20:58PM -0600, Andy Gross wrote:
> + Stanimir
> 
> On Sat, Jan 14, 2017 at 09:49:01PM -0600, Andy Gross wrote:
> > On Fri, Jan 13, 2017 at 04:24:38PM -0700, Jordan Crouse wrote:
> > > On Fri, Jan 13, 2017 at 11:12:41AM -0600, Andy Gross wrote:
> > > > On Mon, Nov 28, 2016 at 12:28:35PM -0700, Jordan Crouse wrote:
> > > > > Add an interface to trigger the remote processor to reinitialize the GPU
> > > > > zap shader on power-up.
> > > > > 
> > > > > Signed-off-by: Jordan Crouse <jcrouse at codeaurora.org>
> > > > > ---
> > > > 
> > > > <snip>
> > > > 
> > > > > +int __qcom_scm_gpu_zap_resume(struct device *dev)
> > > > > +{
> > > > > +	struct qcom_scm_desc desc = {0};
> > > > > +	struct arm_smccc_res res;
> > > > > +	int ret;
> > > > > +
> > > > > +	desc.args[0] = 0;
> > > 
> > > This is an opcode to force the state to resume.
> > > 
> > > QCOM_SCM_BOOT_SET_STATE_RESUME perhaps?  Or something similar but shorter.
> > > 
> > > > > +	desc.args[1] = 13;
> > > 
> > > This is the same as the SCM id of the GPU but I think that is a coincidence.
> > > We've always used it to identify the GPU in this call.
> > > 
> > > QCOM_SCM_BOOT_SET_STATE_GPU would be fine here - or something similar.
> > > 
> > > > Can I get a define here for these two?  Or maybe a comment on what these values
> > > > are?
> > > > 
> > > > > +	desc.arginfo = QCOM_SCM_ARGS(2);
> > > > > +
> > > > > +	ret = qcom_scm_call(dev, QCOM_SCM_SVC_BOOT, 0x0A, &desc, &res);
> > > > 
> > > > Same with the 0xA.  We usually throw a #define in for the command definitions.
> > > 
> > > 0x0A sets the state of the device - for us it is always 0 (resume) and always
> > > the GPU.
> > > 
> > > #define  QCOM_SCM_BOOT_SET_STATE 0x0A
> > > 
> > > > Otherwise this all looks fine.  If you can get back to me with either the values
> > > > or a new patch I can include this in the next pull.
> > > 
> > > I'll make the changes and start the song and dance, but you'll no doubt be
> > > faster than I.
> > 
> > I can just fix up the patch with the above.  Thanks for the additional details.
> 
> The plot thickens.  So I have a patch from Stanimir concerning another SCM call
> that is using the same command and number of arguments.  And it also concerns
> setting state.  I think that we need to roll a common API for setting the state
> and then both of you can call it.  That way we can kill two birds with one
> stone.

I was worried about this, but not this quickly - glad to see that the other
drivers are coming along too.

If you look carefully, you'll note that the values are inverted - the video
state uses 0 to suspend and 1 to resume, and GPU uses 0 to resume and no
suspend. I asked why and got a bunch of shrugging back. Its not a big deal
because your API accounts for this but expect GPU to have a RESUME #define
that is a different value.

> Something along the lines of a function prototype:
> int qcom_scm_set_remote_state(u32 state, u32 id)
> {
> 	return __qcom_scm_set_remote_state(__scm->dev, state, id);
> }
> EXPORT_SYMBOL(qcom_scm_set_remote_state);
> 
> where state is the state you want set, and id is the identifier of the remote
> proc.
>
> Does this make sense for both of your use cases?

Yep - this is fine.

Jordan
-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project