From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 49586606A31B for ; Thu, 5 Nov 2026 17:07:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=L8jmFBfT Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id AEB9910E021; Thu, 5 Nov 2026 17:07:24 +0000 (UTC) Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by gabe.freedesktop.org (Postfix) with ESMTPS id 5D3DF10E1AC for ; Thu, 5 Nov 2026 17:07:18 +0000 (UTC) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 3CBF043497; Thu, 5 Nov 2026 17:07:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F09161F000C1; Thu, 5 Nov 2026 17:07:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793898438; bh=Kpl8+++8QJGKSdrsjHm4Wy9OAm6wG8uG3+wooafG0KE=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=L8jmFBfTZSykGVjmIr1qeuTAW6jB4Cl0JP2SfRJGBUKOCvyzevLenEFC4bVgBkptX XdXPr4ZKOzPA61YZMPaDu9bhZVmeNTyk5+Fah7ntXhrft2phzZc+vok3V5IOFuUgxO fJrDWUhFWx9/EghbV+q5TdYII3n2v6//5n4gtON/bo8Q4zKFAF9x/zDCMk0jYqtKT3 xgUJvoQga5aAV6vtLEqoUWXG4f+qVPcfwwfytd7T92v3Rz+s93sjGJPktScDxqkjKi CEJqMfUZxkDIeRxZJEGU+NoCyTeZ2uGw84fuv39d4qGLny/6zcICiMln4bKOvMzhFC KenIIosFyFrgw== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v2 09/27] drm: Add VRR target frame rate properties To: "Nicolas Frattaroli" Cc: dri-devel@lists.freedesktop.org In-Reply-To: <20261105-vrr-limiter-uapi-v2-9-55f4215be2c2@collabora.com> References: <20261105-vrr-limiter-uapi-v2-0-55f4215be2c2@collabora.com> <20261105-vrr-limiter-uapi-v2-9-55f4215be2c2@collabora.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Thu, 05 Nov 2026 17:07:17 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: sashiko-reviews@lists.linux.dev Sender: "dri-devel" X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 X-Archived-By: Thank you for your contribution! Sashiko AI review found 2 potential issue(= s) to consider: - [Medium] drm: missing DRM_MODE_PROP_ATOMIC flag on VRR limiter CRTC prope= rties - [Medium] drm: missing min <=3D max VRR rate check in drm_atomic_crtc_chec= k() -- commit 221e142e46603679a11c0d1b71599449f1d7a39c Author: Nicolas Frattaroli drm: Add VRR target frame rate properties This commit introduces four CRTC properties (VRR_MIN_NUMERATOR, VRR_MIN_DENOMINATOR, VRR_MAX_NUMERATOR, and VRR_MAX_DENOMINATOR) to allow userspace to configure a target frame rate range for Variable Refresh Rate as numerator/denominator fractions. > diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c > index 9bb761eda59f4..da5c6925c349f 100644 > --- a/drivers/gpu/drm/drm_atomic.c > +++ b/drivers/gpu/drm/drm_atomic.c > @@ -489,6 +489,7 @@ EXPORT_SYMBOL(drm_atomic_get_crtc_state); > static int drm_atomic_crtc_check(const struct drm_crtc_state *old_crtc_s= tate, > const struct drm_crtc_state *new_crtc_state) > { > + const struct drm_crtc_vrr_state *vrr =3D &new_crtc_state->vrr_state; > struct drm_crtc *crtc =3D new_crtc_state->crtc; > =20 > /* NOTE: we explicitly don't enforce constraints such as primary > @@ -544,6 +545,19 @@ static int drm_atomic_crtc_check(const struct drm_cr= tc_state *old_crtc_state, > return -EINVAL; > } > =20 > + /* > + * Reject VRR limiter ranges that only specify one end of the limit, or > + * specify a numerator > 0 with a denominator that is 0. > + */ > + if ((!vrr->vrr_min_n || !vrr->vrr_min_d || > + !vrr->vrr_max_n || !vrr->vrr_max_d) && > + (vrr->vrr_min_n > 0 || vrr->vrr_max_n > 0)) { > + drm_dbg_atomic(crtc->dev, > + "[CRTC:%d:%s] incomplete VRR limiter range\n", > + crtc->base.id, crtc->name); > + return -EINVAL; > + } [Severity: Medium] As reported by Sashiko on RFC [1], should drm_atomic_crtc_check() also reje= ct inverted VRR target frame rate ranges where the minimum rate fraction excee= ds the maximum rate fraction? In include/drm/drm_mode_config.h, the kerneldoc for struct drm_mode_config documents that prop_vrr_max_numerator divided by prop_vrr_max_denominator m= ust result in a frame rate equal to or above prop_vrr_min_numerator divided by prop_vrr_min_denominator. However, drm_atomic_crtc_check() only checks that all four values are non-z= ero when either numerator is positive. If userspace submits an atomic commit via DRM_IOCTL_MODE_ATOMIC with non-zero limiter values where vrr_min_n / vrr_mi= n_d is greater than vrr_max_n / vrr_max_d (for example while vrr_enabled is fal= se, or on a non-HDMI connector), the check succeeds and commits the inverted ra= nge into drm_crtc_state. Would it make sense to check: mul_u32_u32(vrr->vrr_min_n, vrr->vrr_max_d) > mul_u32_u32(vrr->vrr_max_n, vrr->vrr_min_d) when the limiter range is non-zero in drm_atomic_crtc_check()? [ ... ] > diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode= _config.c > index 48a56f23dadbb..da967d60f832a 100644 > --- a/drivers/gpu/drm/drm_mode_config.c > +++ b/drivers/gpu/drm/drm_mode_config.c > @@ -535,6 +535,26 @@ static int drm_mode_create_standard_properties(struc= t drm_device *dev) > return -ENOMEM; > dev->mode_config.prop_vrr_enabled =3D prop; > =20 > + prop =3D drm_property_create_range(dev, 0, "VRR_MIN_NUMERATOR", 0, U32_= MAX); > + if (!prop) > + return -ENOMEM; > + dev->mode_config.prop_vrr_min_numerator =3D prop; > + > + prop =3D drm_property_create_range(dev, 0, "VRR_MIN_DENOMINATOR", 0, U3= 2_MAX); > + if (!prop) > + return -ENOMEM; > + dev->mode_config.prop_vrr_min_denominator =3D prop; > + > + prop =3D drm_property_create_range(dev, 0, "VRR_MAX_NUMERATOR", 0, U32_= MAX); > + if (!prop) > + return -ENOMEM; > + dev->mode_config.prop_vrr_max_numerator =3D prop; > + > + prop =3D drm_property_create_range(dev, 0, "VRR_MAX_DENOMINATOR", 0, U3= 2_MAX); > + if (!prop) > + return -ENOMEM; > + dev->mode_config.prop_vrr_max_denominator =3D prop; [Severity: Medium] As reported by Sashiko on RFC [2], should these four properties be created with the DRM_MODE_PROP_ATOMIC flag in drm_mode_create_standard_properties()? Because flags is passed as 0 to drm_property_create_range(), drm_mode_object_get_properties() exposes these properties to legacy non-ato= mic userspace clients. Non-atomic clients update properties one at a time via DRM_IOCTL_MODE_OBJ_SETPROPERTY: drm_mode_obj_set_property_ioctl() -> set_property_atomic() -> drm_atomic_commit() -> drm_atomic_check_only() -> drm_atomic_crtc_check() Since drm_atomic_crtc_check() rejects any state where only part of the limiter range is non-zero with -EINVAL, a legacy client cannot transition from (0, 0, 0, 0) to an active range or clear an active range back to (0, 0, 0, 0) one property at a time without failing on the intermediate commits. [1] https://lore.kernel.org/r/20260921-vrr-limiter-uapi-v1-13-2fcd7d011646@= collabora.com [2] https://lore.kernel.org/r/20260921-vrr-limiter-uapi-v1-13-2fcd7d011646@= collabora.com --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261105-vrr-limite= r-uapi-v2-0-55f4215be2c2@collabora.com?part=3D9