From nobody Tue Dec 23 12:16:03 2025 Received: from sender4-op-o15.zoho.com (sender4-op-o15.zoho.com [136.143.188.15]) (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 F1EBF374FA for ; Sat, 29 Jun 2024 05:23:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.188.15 ARC-Seal: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719638610; cv=pass; b=pAv3UpSq6/06zj5foUY1CG9Dpk43Vk3w7+1wGWRz8YATj+WntupFmXJDZprd3/A7aF7n3MxfER4DYR8xeDccLMFc4vRUp2AyH49Wv1/CVMRfr3aOhfAAiwK6uQ8IInu8CA9e8pF7y19QhHEGzaYhGsrybnxAJ3TAyWCSwdSKqek= ARC-Message-Signature: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719638610; c=relaxed/simple; bh=sb40Yndd1QV5J124GfSY24yvDpzRWJYgrpqBKCKq3YA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WyUDLtPWCwWzsaXz7NGKzPi8/PkJHe6/AC7qLU2vV/ekBHZI3cP+8D+8gldX1hhsx1FL5D5tzgnMVwwSnjLZgrCrexpC9Upz4jso5Xl3IeYyiI6N5b7ZoCZ1ifNnuETqSUJqYb1sv93ru0MQGoICwEZILoJ4OvOdMOgFmRLZzs0= ARC-Authentication-Results: i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=icenowy.me; spf=pass smtp.mailfrom=icenowy.me; dkim=pass (2048-bit key) header.d=icenowy.me header.i=uwu@icenowy.me header.b=PD5Yikpx; arc=pass smtp.client-ip=136.143.188.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=icenowy.me Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=icenowy.me Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=icenowy.me header.i=uwu@icenowy.me header.b="PD5Yikpx" ARC-Seal: i=1; a=rsa-sha256; t=1719638598; cv=none; d=zohomail.com; s=zohoarc; b=N/pQoJ2HBGvk5OK+rAVXPycZXrx862RBstQIPY3TLRJFlxTQGNm3x5+pdTId6PIFR/xFLKl+zNYPmVdHX/u7stLAqPAXOiRYBSDGbWX0oQ+ZZ2MTBdFPweATWUa2FrJ1xwW0owIMVG2UGCJAwA4pbwtcphMmH9zrfDD48hs/Jtk= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1719638598; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=ZiTmCeUwyWMd9DM1cMRWsanJUulWwCpqnbNYD4zrjzg=; b=XiDgC3JhNqZXq3Dl/co1ZX9jCsgGaeO1sy4ayn2iV7CC/nzYUyRRrkmZ6CL0y39P5nHhg8Eqjn+Rc+pho9NGbri77nRrpO+I7ujk7UUGXAWuoen1utBAvgcCM/ZlsZ4baUYHX/7B/gBJanO+sGmdCcUdqUVGwGlOwHiG3XUX6XA= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=icenowy.me; spf=pass smtp.mailfrom=uwu@icenowy.me; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1719638598; s=zmail2; d=icenowy.me; i=uwu@icenowy.me; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:In-Reply-To:References:MIME-Version:Content-Transfer-Encoding:Message-Id:Reply-To; bh=ZiTmCeUwyWMd9DM1cMRWsanJUulWwCpqnbNYD4zrjzg=; b=PD5Yikpx54BMenJrjK/5RN8Nx43MLhxJbJdCq4ryw9GJhTyAw3y3sT/SEk8dAoI5 dkDAGn61fk51ei0dAE9cs+9R5eXuHNz26yvlI82iu9eg+eqTfLeroKmGzxjTTsafXss gy0M9q1usdBjzdZQf7yHgxn4rHin7T/qN1WOuJ1nqc+tmeU/Cr7dRZyeDgXycSPyGu/ 3E1PxqfdeesDrojoKPJdV4uM1q3J+Xh50PUARjTLX7e4eW5mGV/CZ8WjgeIbPlIVWXc RrdAStixwbiKk+JHHwq/sY2U5jKL9BL3benHiUfI8asoTw8bcipK5dup2XlVHYnpSHM 1zMaMYQkAA== Received: by mx.zohomail.com with SMTPS id 1719638596401770.5863508458222; Fri, 28 Jun 2024 22:23:16 -0700 (PDT) From: Icenowy Zheng To: Christian Koenig , Huang Rui , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , Jiaxun Yang Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Icenowy Zheng Subject: [RFC PATCH 2/2] drm/ttm: downgrade cached to write_combined when snooping not available Date: Sat, 29 Jun 2024 13:22:47 +0800 Message-ID: <20240629052247.2653363-3-uwu@icenowy.me> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240629052247.2653363-1-uwu@icenowy.me> References: <20240629052247.2653363-1-uwu@icenowy.me> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMailClient: External Content-Type: text/plain; charset="utf-8" As we can now acquire the presence of the full DMA coherency (snooping capability) from ttm_device, we can now map the CPU side memory as write-combined when cached is requested and snooping is not avilable. Signed-off-by: Icenowy Zheng --- drivers/gpu/drm/ttm/ttm_bo_util.c | 4 ++++ drivers/gpu/drm/ttm/ttm_tt.c | 4 ++++ include/drm/ttm/ttm_caching.h | 3 ++- 3 files changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo= _util.c index 0b3f4267130c4..6519ce047787d 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_util.c +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c @@ -302,6 +302,10 @@ pgprot_t ttm_io_prot(struct ttm_buffer_object *bo, str= uct ttm_resource *res, caching =3D res->bus.caching; } =20 + /* Downgrade cached mapping for non-snooping devices */ + if (!bo->bdev->dma_coherent && caching =3D=3D ttm_cached) + caching =3D ttm_write_combined; + return ttm_prot_from_caching(caching, tmp); } EXPORT_SYMBOL(ttm_io_prot); diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c index 7b00ddf0ce49f..3335df45fba5e 100644 --- a/drivers/gpu/drm/ttm/ttm_tt.c +++ b/drivers/gpu/drm/ttm/ttm_tt.c @@ -152,6 +152,10 @@ static void ttm_tt_init_fields(struct ttm_tt *ttm, enum ttm_caching caching, unsigned long extra_pages) { + /* Downgrade cached mapping for non-snooping devices */ + if (!bo->bdev->dma_coherent && caching =3D=3D ttm_cached) + caching =3D ttm_write_combined; + ttm->num_pages =3D (PAGE_ALIGN(bo->base.size) >> PAGE_SHIFT) + extra_page= s; ttm->page_flags =3D page_flags; ttm->dma_address =3D NULL; diff --git a/include/drm/ttm/ttm_caching.h b/include/drm/ttm/ttm_caching.h index a18f43e93abab..f92d7911f50e4 100644 --- a/include/drm/ttm/ttm_caching.h +++ b/include/drm/ttm/ttm_caching.h @@ -47,7 +47,8 @@ enum ttm_caching { =20 /** * @ttm_cached: Fully cached like normal system memory, requires that - * devices snoop the CPU cache on accesses. + * devices snoop the CPU cache on accesses. Downgraded to + * ttm_write_combined when the snooping capaiblity is missing. */ ttm_cached }; --=20 2.45.2