From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arto Merilainen Subject: Re: [PATCH 2/3] drm/tegra: Deliver syncpoint base to user space Date: Fri, 11 Oct 2013 13:23:41 +0300 Message-ID: <5257D1AD.9060000@nvidia.com> References: <1381319650-9799-1-git-send-email-amerilainen@nvidia.com> <1381319650-9799-3-git-send-email-amerilainen@nvidia.com> <20131011094352.GB8659@ulmo.nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20131011094352.GB8659@ulmo.nvidia.com> Sender: linux-kernel-owner@vger.kernel.org To: Thierry Reding Cc: Terje Bergstrom , "dri-devel@lists.freedesktop.org" , "linux-tegra@vger.kernel.org" , "linux-kernel@vger.kernel.org" List-Id: dri-devel@lists.freedesktop.org On 10/11/2013 12:43 PM, Thierry Reding wrote: > * PGP Signed by an unknown key > > On Wed, Oct 09, 2013 at 02:54:09PM +0300, Arto Merilainen wrote: >> This patch makes the necessary additions to deliver syncpoint base >> to the user space. >> >> This patch splits the index field in the drm_tegra_get_syncpt structure >> into three separate fields (index, support_base, base_id). This allows >> to keep compatibility over kernel versions: >> - The placing of index field stays constant and therefore the interface >> should stay compatible with earlier userspace versions. >> - The old index field was input-only and it was not supposed to be read >> afterwards. Delivering data back in the same field should not introduce >> regressions to any old user space applications. >> - Old kernels left support_base and base_id fields intact (zero) and >> hence the new user space applications get the correct response from >> the kernel (=syncpoint does not have a base). >> >> Signed-off-by: Arto Merilainen >> --- >> drivers/gpu/host1x/drm/drm.c | 2 ++ >> include/uapi/drm/tegra_drm.h | 4 +++- >> 2 files changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/host1x/drm/drm.c b/drivers/gpu/host1x/drm/drm.c >> index 8c61cee..4251563 100644 >> --- a/drivers/gpu/host1x/drm/drm.c >> +++ b/drivers/gpu/host1x/drm/drm.c >> @@ -468,6 +468,8 @@ static int tegra_get_syncpt(struct drm_device *drm, void *data, >> >> syncpt = context->client->syncpts[args->index]; >> args->id = host1x_syncpt_id(syncpt); >> + args->support_base = syncpt->base ? 1 : 0; >> + args->base_id = syncpt->base ? syncpt->base->id : 0; >> >> return 0; >> } >> diff --git a/include/uapi/drm/tegra_drm.h b/include/uapi/drm/tegra_drm.h >> index 73bde4e..7a79ca5 100644 >> --- a/include/uapi/drm/tegra_drm.h >> +++ b/include/uapi/drm/tegra_drm.h >> @@ -61,7 +61,9 @@ struct drm_tegra_close_channel { >> >> struct drm_tegra_get_syncpt { >> __u64 context; >> - __u32 index; >> + __u16 index; >> + __u8 support_base; >> + __u8 base_id; >> __u32 id; > > I don't like this. Can't we just add a separate IOCTL? Something like: Sure. This felt like a good idea, but I must admit I had a bit mixed feelings after looking my own explanation why this would be ok... - Arto