From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 481A020F98 for ; Fri, 21 Jul 2023 19:14:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C0ED2C433C7; Fri, 21 Jul 2023 19:14:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689966841; bh=luhuEkCFcuotNW20mzKglxjcm3aA8LfS4oaMi4oxZD4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IxzftLnA9gNsrDQsSZUy1TTw+lDDoY07m8m8ByE29l60v8DSg9FfAvP6ufP073nJb FZJblSdf2J9OLkXNKg9vv7UbmobmLUnUPH6fwgkum/XBJFt4fzasfvzEppRi52LSZD oRpBHW2SoNsManZWCXpEpTZi4CV0W9CJUHB1J6k4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Brian Norris , Sean Paul Subject: [PATCH 5.15 487/532] drm/atomic: Allow vblank-enabled + self-refresh "disable" Date: Fri, 21 Jul 2023 18:06:31 +0200 Message-ID: <20230721160640.926896634@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230721160614.695323302@linuxfoundation.org> References: <20230721160614.695323302@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Brian Norris commit 9d0e3cac3517942a6e00eeecfe583a98715edb16 upstream. The self-refresh helper framework overloads "disable" to sometimes mean "go into self-refresh mode," and this mode activates automatically (e.g., after some period of unchanging display output). In such cases, the display pipe is still considered "on", and user-space is not aware that we went into self-refresh mode. Thus, users may expect that vblank-related features (such as DRM_IOCTL_WAIT_VBLANK) still work properly. However, we trigger the WARN_ONCE() here if a CRTC driver tries to leave vblank enabled. Add a different expectation: that CRTCs *should* leave vblank enabled when going into self-refresh. This patch is preparation for another patch -- "drm/rockchip: vop: Leave vblank enabled in self-refresh" -- which resolves conflicts between the above self-refresh behavior and the API tests in IGT's kms_vblank test module. == Some alternatives discussed: == It's likely that on many display controllers, vblank interrupts will turn off when the CRTC is disabled, and so in some cases, self-refresh may not support vblank. To support such cases, we might consider additions to the generic helpers such that we fire vblank events based on a timer. However, there is currently only one driver using the common self-refresh helpers (i.e., rockchip), and at least as of commit bed030a49f3e ("drm/rockchip: Don't fully disable vop on self refresh"), the CRTC hardware is powered enough to continue to generate vblank interrupts. So we chose the simpler option of leaving vblank interrupts enabled. We can reevaluate this decision and perhaps augment the helpers if/when we gain a second driver that has different requirements. v3: * include discussion summary v2: * add 'ret != 0' warning case for self-refresh * describe failing test case and relation to drm/rockchip patch better Cc: # dependency for "drm/rockchip: vop: Leave # vblank enabled in self-refresh" Signed-off-by: Brian Norris Signed-off-by: Sean Paul Link: https://patchwork.freedesktop.org/patch/msgid/20230109171809.v3.1.I3904f697863649eb1be540ecca147a66e42bfad7@changeid Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_atomic_helper.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -1115,7 +1115,16 @@ disable_outputs(struct drm_device *dev, continue; ret = drm_crtc_vblank_get(crtc); - WARN_ONCE(ret != -EINVAL, "driver forgot to call drm_crtc_vblank_off()\n"); + /* + * Self-refresh is not a true "disable"; ensure vblank remains + * enabled. + */ + if (new_crtc_state->self_refresh_active) + WARN_ONCE(ret != 0, + "driver disabled vblank in self-refresh\n"); + else + WARN_ONCE(ret != -EINVAL, + "driver forgot to call drm_crtc_vblank_off()\n"); if (ret == 0) drm_crtc_vblank_put(crtc); }