From mboxrd@z Thu Jan 1 00:00:00 1970 From: YoungJun Cho Subject: Re: [PATCH v6 10/14] drm/panel: add S6E3FA0 driver Date: Tue, 22 Jul 2014 19:20:14 +0900 Message-ID: <53CE3ADE.9050905@samsung.com> References: <1405587689-1466-1-git-send-email-yj44.cho@samsung.com> <1405587689-1466-11-git-send-email-yj44.cho@samsung.com> <20140717103645.GD17877@ulmo> <53C87D2F.9000906@samsung.com> <53CCD5A8.6090406@samsung.com> <20140721091917.GK8843@ulmo> <53CCF70A.5010403@samsung.com> <53CDDD61.6000005@samsung.com> <20140722074935.GC18258@ulmo> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-reply-to: <20140722074935.GC18258@ulmo> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Thierry Reding Cc: mark.rutland@arm.com, devicetree@vger.kernel.org, linux-samsung-soc@vger.kernel.org, pawel.moll@arm.com, ijc+devicetree@hellion.org.uk, Tomi Valkeinen , Paul Mundt , sw0312.kim@samsung.com, dri-devel@lists.freedesktop.org, Andrzej Hajda , kyungmin.park@samsung.com, robh+dt@kernel.org, galak@codeaurora.org, kgene.kim@samsung.com, Guennadi Liakhovetski List-Id: devicetree@vger.kernel.org Hi Thierry, On 07/22/2014 04:49 PM, Thierry Reding wrote: > On Tue, Jul 22, 2014 at 12:41:21PM +0900, YoungJun Cho wrote: >> On 07/21/2014 08:18 PM, Andrzej Hajda wrote: >>> On 07/21/2014 11:19 AM, Thierry Reding wrote: >>>> On Mon, Jul 21, 2014 at 10:56:08AM +0200, Andrzej Hajda wrote: >>>>> On 07/18/2014 03:49 AM, YoungJun Cho wrote: >>>>>> On 07/17/2014 07:36 PM, Thierry Reding wrote: >>>>>>> On Thu, Jul 17, 2014 at 06:01:25PM +0900, YoungJun Cho wrote: > [...] >>>>>>>> +static void s6e3fa0_read_mtp_id(struct s6e3fa0 *ctx) >>>>>>>> +{ >>>>>>>> + unsigned char id[MTP_ID_LEN]; >>>>>>>> + int ret; >>>>>>>> + >>>>>>>> + s6e3fa0_set_maximum_return_packet_size(ctx, MTP_ID_LEN); >>>>>>>> + ret = s6e3fa0_dcs_read(ctx, MIPI_DCS_GET_DISPLAY_ID, id, MTP_ID_LEN); >>>>>>> This also looks like a standard DCS command. I can't find it in either >>>>>>> v1.01 nor v1.02 of the specification, though. Do you know where it's >>>>>>> specified? >>>>>>> >>>>>> Yes, I also can't find it in DCS specification and there is no special >>>>>> description in panel datasheet. >>>>>> But as it is declared in "include/video/mipi_display.h", so I think it >>>>>> is a standard one. >>>>> >>>>> On page 9 of the "Introduction of MIPI by Renesas" [2] there is info >>>>> it is a part of "Nokia I/F command list", I guess it is kind of alpha >>>>> version of MIPI DCS. >>>>> >>>>> [2]: http://wenku.baidu.com/view/658fab68af1ffc4ffe47acbe.html >>>> >>>> That link is the only one which contains "Nokia I/F command list" on the >>>> internet (that is, according to Google). But since this is already part >>>> of the mipi_display.h header file we may as well use it. >>>> >>>> I wonder if perhaps the READ_DDB_START and READ_DDB_CONTINUE commands >>>> could be used as a replacement for this display ID. >>>> >> >> There is a simple description for "Read DDB Start(A1H)" like below. >> - This command returns supplier identification and display module model / >> revision information. >> - NOTE: This information is not the same what Read IDs(04H) command is >> returning. >> >> For reference, Read IDs(04H) description is like below. >> - This read command returns 24-bit display identification information. >> - The first read byte identifies the OLED module's manufacturer. >> - The Second read byte is used to track the OLED module/driver version. >> - The third read byte identifies the OLED module/driver. > > Okay, that explains things a little better. Can you point me to the > document that this is from? Sorry, I forgot to write specification name. This specification is s6e3fa0 data sheet and it is confidential. So I quoted only that portion. > > But what I was trying to say is that if the Read IDs command isn't an > official DCS command, maybe it would be a better idea to use the DDB > instead. I assume that even if it isn't the same information it would > at least be a superset and therefore a suitable replacement. This panel has several versions and each should set specific tuning value especially for AID, ELVSS and etc. (Current is suitable for id[2] == 0x23). I'll check READ_DDB_START & READ_DDB_CONTINUE result and try to use them if it is possible. Thank you. Best regards YJ > > Thierry >