Re: [PATCH v2 04/10] cxl/pci: Use synchronous API for DOE

[Lukas Wunner <lukas@wunner.de>]

On Tue, Jan 24, 2023 at 11:01:27AM +0000, Jonathan Cameron wrote:
> On Mon, 23 Jan 2023 11:14:00 +0100 Lukas Wunner <lukas@wunner.de> wrote:
> > A synchronous API for DOE has just been introduced.  Convert CXL CDAT
> > retrieval over to it.
> 
> The clean up here gives opportunities for 'right sizing' at least
> the response to reading the header. The others are harder was we
> don't know what each one is going to be.
> May make more sense as a follow on patch though. 

Thy will be done:

https://lore.kernel.org/linux-pci/49c5299afc660ac33fee9a116ea37df0de938432.1676043318.git.lukas@wunner.de/


> > -		DECLARE_CDAT_DOE_TASK(CDAT_DOE_REQ(entry_handle), t);
> > +		u32 request = CDAT_DOE_REQ(entry_handle);
> > +		u32 response[32];
> 
> As above, this is still a bit random.
> Things we might be reading.
> DSMAS: 6 dword
> DSLBIS: 6 dword
> DSIS: 2 dword
> DSEMTS: 6 dword
> SSLBIS: 4 dword + 2 * entires dwords.  This can get huge - as
> can include p2p as well as the smaller usp / dsp set.
> 
> Right now we aren't reading from switches though so we can fix
> that later (I posted an RFC for switches ages ago, but haven't
> gotten back to it since then)
> 
> So for now probably leave this one at the 32 dwords.

I found a way to avoid a response buffer altogether.

Thanks,

Lukas