From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Subject: Re: [PATCH] drm: rcar-du: Add r8a77980 support Date: Fri, 13 Sep 2019 12:03:59 +0300 Message-ID: <20190913090359.GC29992@pendragon.ideasonboard.com> References: <20190911192502.16609-1-kieran.bingham+renesas@ideasonboard.com> <70b94265-69f3-d18f-1b67-b5b814723b1b@cogentembedded.com> <20190913082129.lvusbp6pbcayqh5r@verge.net.au> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Content-Disposition: inline In-Reply-To: <20190913082129.lvusbp6pbcayqh5r@verge.net.au> Sender: linux-kernel-owner@vger.kernel.org To: Simon Horman Cc: Sergei Shtylyov , Kieran Bingham , linux-renesas-soc@vger.kernel.org, David Airlie , Daniel Vetter , "open list:DRM DRIVERS FOR RENESAS" , open list List-Id: dri-devel@lists.freedesktop.org Hello, On Fri, Sep 13, 2019 at 10:21:29AM +0200, Simon Horman wrote: > On Thu, Sep 12, 2019 at 01:00:41PM +0300, Sergei Shtylyov wrote: > > On 11.09.2019 22:25, Kieran Bingham wrote: > > > > > Add direct support for the r8a77980 (V3H). > > > > > > The V3H shares a common, compatible configuration with the r8a77970 > > > (V3M) so that device info structure is reused. > > > > Do we really need to add yet another compatible in this case? > > I just added r8a77970 to the compatible prop in the r8a77980 DT. That's why > > a patch like this one didn't get posted by me. > > The reason for having per-SoC compat strings is that the IP blocks > are not versioned and while we can observe that there are similarities > between, f.e. the DU on the r8a77970 and r8a77980, we can't be certain that > differences may not emerge at some point. By having per-SoC compat strings > we have the flexibility for the driver to address any such differences as > the need arises. > > My recollection is that this scheme has been adopted for non-versioned > Renesas IP blocks since June 2015 and uses of this scheme well before that. Sure, but we could use compatible = "renesas,du-r8a77980", "renesas,du-r8a77970"; in DT without updating the driver. If the r8a77980 turns out to be different, we'll then update the driver without a need to modify DT. I'm fine either way, so Reviewed-by: Laurent Pinchart > > > Signed-off-by: Kieran Bingham > > Reviewed-by: Simon Horman -- Regards, Laurent Pinchart