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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 5 Oct 2018 16:03:14 -0400 Received: from b01ledav001.gho.pok.ibm.com (b01ledav001.gho.pok.ibm.com [9.57.199.106]) by b01cxnp22034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w95K3D2w2032104 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 5 Oct 2018 20:03:13 GMT Received: from b01ledav001.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0FD542805E; Fri, 5 Oct 2018 16:00:48 -0400 (EDT) Received: from b01ledav001.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3445C28058; Fri, 5 Oct 2018 16:00:47 -0400 (EDT) Received: from [9.41.179.222] (unknown [9.41.179.222]) by b01ledav001.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 5 Oct 2018 16:00:47 -0400 (EDT) Subject: Re: [PATCH v3 2/2] media: platform: Add Aspeed Video Engine driver To: Hans Verkuil , Eddie James , linux-kernel@vger.kernel.org Cc: mark.rutland@arm.com, devicetree@vger.kernel.org, linux-aspeed@lists.ozlabs.org, andrew@aj.id.au, openbmc@lists.ozlabs.org, robh+dt@kernel.org, mchehab@kernel.org, linux-media@vger.kernel.org References: <1537903629-14003-1-git-send-email-eajames@linux.ibm.com> <1537903629-14003-3-git-send-email-eajames@linux.ibm.com> <373d2ca3-a6cd-8d87-2bbc-613d65305170@xs4all.nl> From: Eddie James Date: Fri, 5 Oct 2018 15:03:11 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <373d2ca3-a6cd-8d87-2bbc-613d65305170@xs4all.nl> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 18100520-0040-0000-0000-0000047BE17A X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009825; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000267; SDB=6.01098370; UDB=6.00568107; IPR=6.00878411; MB=3.00023633; MTD=3.00000008; XFM=3.00000015; UTC=2018-10-05 20:03:16 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18100520-0041-0000-0000-00000883EE81 Message-Id: <8476027d-80d5-2787-944b-eb3f5af717c3@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-10-05_10:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1810050191 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/04/2018 08:12 AM, Hans Verkuil wrote: > On 10/03/18 22:43, Eddie James wrote: >> >> On 09/28/2018 06:30 AM, Hans Verkuil wrote: >>> On 09/25/2018 09:27 PM, Eddie James wrote: >>>> The Video Engine (VE) embedded in the Aspeed AST2400 and AST2500 SOCs >>>> can capture and compress video data from digital or analog sources. With >>>> the Aspeed chip acting a service processor, the Video Engine can capture >>>> the host processor graphics output. >>>> >>>> Add a V4L2 driver to capture video data and compress it to JPEG images. >>>> Make the video frames available through the V4L2 streaming interface. >>>> >>>> Signed-off-by: Eddie James >>>> + } >>>> + >>>> + video->height = (bottom - top) + 1; >>>> + video->width = (right - left) + 1; >>>> + size = video->height * video->width; >>> It looks like you can actually determine the blanking width/height and >>> possibly even more detailed information that would be very useful to >>> show with the DV_TIMINGS ioctls. >> Hmm. This information is related to the video signal captured from the >> host. That information has nothing to do with the buffer that is >> compressed and grabbed by the driver and ultimately provided to >> userspace. Isn't the timing information meaningless for JPEG frames? > It helps in debugging. Basically you are implementing a receiver for a > video signal. So if for some reason you cannot support the video timings > that the host sends, then it is very useful to have QUERY_DV_TIMINGS report > as much information about the signal as possible. > > BTW, out of curiosity, how are the host video signals connected to the > aspeed? Is it still a VGA video signal? > > Looking at product briefs it appears that it is VGA. So I guess the aspeed > 'sniffs' the VGA signals from the host and can capture the video that way. > Is that correct? I believe it is a VGA signal from the host, but the Aspeed Video Engine somewhat abstracts that away; not all the signal information that the engine is receiving is available to the BMC interface. I did add the timing information I could access to the latest patch set. As you say, it could be useful for debugging if weird things are happening. Thanks! Eddie > > If so, then this driver is a VGA receiver and should act like that. > The host can configure its VGA transmitter to invalid timings, or weird > values, and you need to be able to handle that in your driver. > >> Forgot to include this question in my previous reply, sorry for the >> additional mail. > No problem! Happy to help. > > Regards, > > Hans >