From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Osipenko Subject: Re: [RFC] Host1x/TegraDRM UAPI Date: Thu, 25 Jun 2020 02:11:21 +0300 Message-ID: References: <9b06b7ec-f952-2561-7afb-5653514cd5d3@kapsi.fi> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <9b06b7ec-f952-2561-7afb-5653514cd5d3-/1wQRMveznE@public.gmane.org> Content-Language: en-US Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mikko Perttunen , Thierry Reding , Jon Hunter , David Airlie , Daniel Vetter , sumit.semwal-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, gustavo-THi1TnShQwVAfugRpC6u6w@public.gmane.org Cc: "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , dri-devel , talho-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, bhuntsman-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org List-Id: linux-tegra@vger.kernel.org 23.06.2020 15:09, Mikko Perttunen пишет: > /* Command is an opcode gather from a GEM handle */ > #define DRM_TEGRA_SUBMIT_COMMAND_GATHER             0 > /* Command is an opcode gather from a user pointer */ > #define DRM_TEGRA_SUBMIT_COMMAND_GATHER_UPTR        1 I'm a bit dubious about whether we really need to retain the non-UPTR variant. The memory-copying overhead is negligible because cmdstream's data usually is hot in CPU's cache IIRC, the most (if not all) of the modern DRM drivers drivers use the usrptr-only for the cmdstream. At least there is no any real-world userspace example today that could benefit from a non-UPTR variant. I'm suggesting to leave out the non-UPTR gather variant for now, keeping it in mind as a potential future extension of the submission UAPI. Any objections?