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Tue, 07 Apr 2020 01:26:40 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id DB5F6C4478F; Tue, 7 Apr 2020 01:26:38 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: abhinavk) by smtp.codeaurora.org (Postfix) with ESMTPSA id 1CA25C433D2; Tue, 7 Apr 2020 01:26:38 +0000 (UTC) MIME-Version: 1.0 Date: Mon, 06 Apr 2020 18:26:38 -0700 From: abhinavk@codeaurora.org To: Jani Nikula Subject: Re: [PATCH v2 16/17] drm: Nuke mode->private_flags In-Reply-To: <87r1x1kmgr.fsf@intel.com> References: <20200403204008.14864-1-ville.syrjala@linux.intel.com> <20200403204008.14864-17-ville.syrjala@linux.intel.com> <7cd8b081a383125732dbddd32116e46e@codeaurora.org> <87r1x1kmgr.fsf@intel.com> Message-ID: X-Sender: abhinavk@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sam Ravnborg , jeykumar@quicinc.com, Daniel Vetter , intel-gfx@lists.freedesktop.org, Emil Velikov , dri-devel@lists.freedesktop.org, aravindh@quicinc.com, nganji@quicinc.com, pdhaval@quicinc.com, sean@poorly.run Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Hi Jani On 2020-04-06 02:11, Jani Nikula wrote: > On Fri, 03 Apr 2020, abhinavk@codeaurora.org wrote: >> Hi Ville >> >> Thanks for the patch. >> >> Our understanding of private_flags was that we can use it within our >> drivers to handle vendor specific features. >> Hence we do have several features in our downstream drivers as well as >> some planned work based on this. >> >> This was the only method to pass around and consume the driver only >> information which we have been using. >> >> In the current qualcomm upstream display drivers, the only usage of >> the >> mode->private_flags is what you have removed in >> https://patchwork.kernel.org/patch/11473497/. >> >> However, for other projects which do not use upstream drivers yet, we >> have several features already which are using the mode->private_flags. >> >> We do have a plan to remove the usage of mode->private_flags for those >> drivers as well but its not ready yet. >> >> These downstream drivers still use the upstream drm files for >> compilation. >> >> So how it works is we use all the headers under include/drm and also >> the >> files under drivers/gpu/drm as-it-is from upstream but maintain our >> drivers on top of this. >> >> Removing this will result in compilation failures for us in the near >> term. >> >> Can we keep this one as-it-is and when our changes are ready to post >> it >> upstream we shall remove private_flags from the drm_modes.h > > If your driver were upstream, Ville would have fixed it in the process > of removing private_flags. It would be part of this patch series. That > is the only guarantee you get for kernel internal APIs, and you only > get > that guarantee for drivers in the upstream kernel. Otherwise, all bets > are off. > > Taking all the upstream considerations into account is complicated > enough. It is simply not reasonable to hold back internal kernel > changes > due to out-of-tree or downstream drivers. I know it is painful, but > that's the cost of maintaining a driver out-of-tree. > > Sorry, but no. Further reading [1]. > > > BR, > Jani. > > > [1] > https://www.kernel.org/doc/html/latest/process/stable-api-nonsense.html Thanks for the response. We will plan to remove mode->private_flags in our downstream driver as well. Abhinav _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel