Re: [PATCH v6 10/14] drm/panel: add S6E3FA0 driver

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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


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