From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B4B3C4167D for ; Wed, 8 Nov 2023 10:14:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344207AbjKHKOk (ORCPT ); Wed, 8 Nov 2023 05:14:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46626 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229924AbjKHKOj (ORCPT ); Wed, 8 Nov 2023 05:14:39 -0500 Received: from madras.collabora.co.uk (madras.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e5ab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E10EA1726; Wed, 8 Nov 2023 02:14:36 -0800 (PST) Received: from [100.98.136.55] (cola.collaboradmins.com [195.201.22.229]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: benjamin.gaignard) by madras.collabora.co.uk (Postfix) with ESMTPSA id A6CAC6601F0B; Wed, 8 Nov 2023 10:14:34 +0000 (GMT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1699438475; bh=Ilw8GxRpfkU8nyO7ThH/MgVP6lonMiPetYieJPU0Cow=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=hHjoK8FPqHSHyBhzaFy6eW7GzVotn5vdvoEioMcANArq7J2J1ytkv4eCc4fTT5t0X OlCq1uce0ltMYMgTNOASWoAVRC1qjEy3iCmmdpo/9cIKLTluL1dfBAdbLpHIdsiOgY CJvbGJ37rBjjrT6PWd4FH0DWvEF32FuWY+0BUkX7l4ie98OYRZv5NLnLsbEB7qe8YS LGQotB/uscM5F8dIMURWokA7i4k/eVrIQcmMLoZDIRefe6RPXYngQt8CTf7C6Fnxaz 4JsOBmJJ3oFP88T+cl2l/zFCwYEiHL/lMPCKPNbvocAI5f/RgPnhMrloEOPkbI7NVy 1mwwognoYyNrQ== Message-ID: Date: Wed, 8 Nov 2023 11:14:32 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v14 02/56] media: videobuf2: Rework offset 'cookie' encoding pattern To: Tomasz Figa Cc: mchehab@kernel.org, m.szyprowski@samsung.com, ming.qian@nxp.com, ezequiel@vanguardiasur.com.ar, p.zabel@pengutronix.de, gregkh@linuxfoundation.org, hverkuil-cisco@xs4all.nl, nicolas.dufresne@collabora.com, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-rockchip@lists.infradead.org, linux-staging@lists.linux.dev, kernel@collabora.com References: <20231031163104.112469-1-benjamin.gaignard@collabora.com> <20231031163104.112469-3-benjamin.gaignard@collabora.com> <20231108062322.l2k2n2jlpoaa4tws@chromium.org> Content-Language: en-US From: Benjamin Gaignard In-Reply-To: <20231108062322.l2k2n2jlpoaa4tws@chromium.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 08/11/2023 à 07:23, Tomasz Figa a écrit : > Hi Benjamin, > > On Tue, Oct 31, 2023 at 05:30:10PM +0100, Benjamin Gaignard wrote: >> Change how offset 'cookie' field value is computed to make possible >> to use more buffers. >> The maximum number of buffers depends of PAGE_SHIFT value and can >> go up to 0x7fff when PAGE_SHIFT = 12. >> With this encoding pattern we know the maximum number that a queue >> could store so we can check it at queue init time. >> It also make easier and faster to find buffer and plane from using >> the offset field. >> Change __find_plane_by_offset() prototype to return the video buffer >> itself rather than it index. >> >> Signed-off-by: Benjamin Gaignard >> --- >> .../media/common/videobuf2/videobuf2-core.c | 73 +++++++++---------- >> 1 file changed, 35 insertions(+), 38 deletions(-) >> > Thanks a lot for working on this series. Just one comment inline. > >> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c >> index a5e57affeb30..09be8e026044 100644 >> --- a/drivers/media/common/videobuf2/videobuf2-core.c >> +++ b/drivers/media/common/videobuf2/videobuf2-core.c >> @@ -31,6 +31,11 @@ >> >> #include >> >> +#define PLANE_INDEX_SHIFT (PAGE_SHIFT + 3) >> +#define PLANE_INDEX_MASK 0x7 > Could we somehow ensure that it indeed matches VIDEO_MAX_PLANES? > > One thing that comes to my mind would be > > #define PLANE_INDEX_BITS 3 > #define PLANE_INDEX_SHIFT (PAGE_SHIFT + PLANE_INDEX_BITS) > #define PLANE_INDEX_MASK BIT_MASK(PLANE_INDEX_BITS) > > BUILD_BUG_ON(BIT(PLANE_INDEX_BITS) != VIDEO_MAX_PLANES); > > Alternatively we could change the videodev2.h, so that we have > > #define VIDEO_MAX_PLANES_BITS 3 > #define VIDEO_MAX_PLANES (1U < VIDEO_MAX_PLANES_BITS) > > and then we can just VIDEO_MAX_PLANES_BITS in our definitions in this file > and no checks would be necessary. I would prefer this solution. Hans should I do that in an other patch ? Regards, Benjamin > > Best regards, > Tomasz > >> +#define MAX_BUFFER_INDEX BIT_MASK(30 - PLANE_INDEX_SHIFT) >> +#define BUFFER_INDEX_MASK (MAX_BUFFER_INDEX - 1) >> + >> static int debug; >> module_param(debug, int, 0644); >> >> @@ -358,21 +363,27 @@ static void __setup_offsets(struct vb2_buffer *vb) >> unsigned int plane; >> unsigned long offset = 0; >> >> - if (vb->index) { >> - struct vb2_buffer *prev = q->bufs[vb->index - 1]; >> - struct vb2_plane *p = &prev->planes[prev->num_planes - 1]; >> - >> - offset = PAGE_ALIGN(p->m.offset + p->length); >> - } >> + /* >> + * The offset "cookie" value has the following constraints: >> + * - a buffer can have up to 8 planes. >> + * - v4l2 mem2mem uses bit 30 to distinguish between >> + * OUTPUT (aka "source", bit 30 is 0) and >> + * CAPTURE (aka "destination", bit 30 is 1) buffers. >> + * - must be page aligned >> + * That led to this bit mapping when PAGE_SHIFT = 12: >> + * |30 |29 15|14 12|11 0| >> + * |DST_QUEUE_OFF_BASE|buffer index|plane index| 0 | >> + * where there are 15 bits to store the buffer index. >> + * Depending on PAGE_SHIFT value we can have fewer bits >> + * to store the buffer index. >> + */ >> + offset = vb->index << PLANE_INDEX_SHIFT; >> >> for (plane = 0; plane < vb->num_planes; ++plane) { >> - vb->planes[plane].m.offset = offset; >> + vb->planes[plane].m.offset = offset + (plane << PAGE_SHIFT); >> >> dprintk(q, 3, "buffer %d, plane %d offset 0x%08lx\n", >> vb->index, plane, offset); >> - >> - offset += vb->planes[plane].length; >> - offset = PAGE_ALIGN(offset); >> } >> } >> >> @@ -2188,10 +2199,9 @@ EXPORT_SYMBOL_GPL(vb2_core_streamoff); >> * __find_plane_by_offset() - find plane associated with the given offset >> */ >> static int __find_plane_by_offset(struct vb2_queue *q, unsigned long offset, >> - unsigned int *_buffer, unsigned int *_plane) >> + struct vb2_buffer **vb, unsigned int *plane) >> { >> - struct vb2_buffer *vb; >> - unsigned int buffer, plane; >> + unsigned int buffer; >> >> /* >> * Sanity checks to ensure the lock is held, MEMORY_MMAP is >> @@ -2209,24 +2219,15 @@ static int __find_plane_by_offset(struct vb2_queue *q, unsigned long offset, >> return -EBUSY; >> } >> >> - /* >> - * Go over all buffers and their planes, comparing the given offset >> - * with an offset assigned to each plane. If a match is found, >> - * return its buffer and plane numbers. >> - */ >> - for (buffer = 0; buffer < q->num_buffers; ++buffer) { >> - vb = q->bufs[buffer]; >> + /* Get buffer and plane from the offset */ >> + buffer = (offset >> PLANE_INDEX_SHIFT) & BUFFER_INDEX_MASK; >> + *plane = (offset >> PAGE_SHIFT) & PLANE_INDEX_MASK; >> >> - for (plane = 0; plane < vb->num_planes; ++plane) { >> - if (vb->planes[plane].m.offset == offset) { >> - *_buffer = buffer; >> - *_plane = plane; >> - return 0; >> - } >> - } >> - } >> + if (buffer >= q->num_buffers || *plane >= q->bufs[buffer]->num_planes) >> + return -EINVAL; >> >> - return -EINVAL; >> + *vb = q->bufs[buffer]; >> + return 0; >> } >> >> int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type, >> @@ -2306,7 +2307,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma) >> { >> unsigned long offset = vma->vm_pgoff << PAGE_SHIFT; >> struct vb2_buffer *vb; >> - unsigned int buffer = 0, plane = 0; >> + unsigned int plane = 0; >> int ret; >> unsigned long length; >> >> @@ -2335,12 +2336,10 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma) >> * Find the plane corresponding to the offset passed by userspace. This >> * will return an error if not MEMORY_MMAP or file I/O is in progress. >> */ >> - ret = __find_plane_by_offset(q, offset, &buffer, &plane); >> + ret = __find_plane_by_offset(q, offset, &vb, &plane); >> if (ret) >> goto unlock; >> >> - vb = q->bufs[buffer]; >> - >> /* >> * MMAP requires page_aligned buffers. >> * The buffer length was page_aligned at __vb2_buf_mem_alloc(), >> @@ -2368,7 +2367,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma) >> if (ret) >> return ret; >> >> - dprintk(q, 3, "buffer %d, plane %d successfully mapped\n", buffer, plane); >> + dprintk(q, 3, "buffer %u, plane %d successfully mapped\n", vb->index, plane); >> return 0; >> } >> EXPORT_SYMBOL_GPL(vb2_mmap); >> @@ -2382,7 +2381,7 @@ unsigned long vb2_get_unmapped_area(struct vb2_queue *q, >> { >> unsigned long offset = pgoff << PAGE_SHIFT; >> struct vb2_buffer *vb; >> - unsigned int buffer, plane; >> + unsigned int plane; >> void *vaddr; >> int ret; >> >> @@ -2392,12 +2391,10 @@ unsigned long vb2_get_unmapped_area(struct vb2_queue *q, >> * Find the plane corresponding to the offset passed by userspace. This >> * will return an error if not MEMORY_MMAP or file I/O is in progress. >> */ >> - ret = __find_plane_by_offset(q, offset, &buffer, &plane); >> + ret = __find_plane_by_offset(q, offset, &vb, &plane); >> if (ret) >> goto unlock; >> >> - vb = q->bufs[buffer]; >> - >> vaddr = vb2_plane_vaddr(vb, plane); >> mutex_unlock(&q->mmap_lock); >> return vaddr ? (unsigned long)vaddr : -EINVAL; >> -- >> 2.39.2 >>