Re: [PATCH] drm/msm/dsi: add support for dsi test pattern generator

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Hi Abhinav,

On 7/16/21 2:01 AM, abhinavk@xxxxxxxxxxxxxx wrote:
Hi Marijn

Sorry for the late response.


Apologies from my side as well.

[...]

+static void msm_dsi_host_cmd_test_pattern_setup(struct msm_dsi_host
*msm_host)
+{
+	u32 reg;
+
+	reg = dsi_read(msm_host, REG_DSI_TEST_PATTERN_GEN_CTRL);
+
+	dsi_write(msm_host, REG_DSI_TEST_PATTERN_GEN_CMD_MDP_INIT_VAL0,
0xff);
+
+	reg |= (0x3 << 0x8);
+	dsi_write(msm_host, REG_DSI_TEST_PATTERN_GEN_CTRL, reg);
+	/* draw checkered rectangle pattern */
+	dsi_write(msm_host, REG_DSI_TPG_MAIN_CONTROL2, (0x1 << 0x7));


How about BIT(7)?

You mean BIT(7) of REG_DSI_TPG_MAIN_CONTROL2? Thats what this is right?
Did you mean some other bit?


I meant to replace (0x1 << 0x7) with BIT(7), but replacing it with DSI_TPG_MAIN_CONTROL2_CMD_MDP0_CHECKERED_RECTANGLE_PATTERN is even better, thanks.



On SM6125 this seems to change the color intensity of the pattern; it
is always colored lines of a few pixels wide alternating R, B and G
from left to right.  Is it possible to document the meaning and
available values of these registers, especially if they differ between
SoC / DSI block?


I have requested access for SM6125, will check this register on that to
see if there
is any difference.

Are you saying you are not seeing a rectangular checkered pattern while
testing?


Correct. It's fixed now, and this patch already proves its usefulness! We had two minor configuration issues, and are now seeing the squares just like on the other SoCs. Meaning we can finally move on to configuring the DPU, thanks!

Also are you testing on command mode or video mode?


Command mode, if it's still worth anything.

As requested by Rob, I will add the bit definitions and update the
dsi.xml.h in the
next patchset for the registers and the bits which I am using here.

With that the meaning of these bits will be more clear.

I dont think I will be able to document all the bits because the goal of
this patch
was only to draw a test pattern to help with validation. Different bits
of the REG_DSI_TPG_MAIN_CONTROL2
register only draw different patterns so the goal wasnt that we can draw
any pattern, it was just to
draw some pattern on the screen.

When we add support for all other patterns, we can expose those bits as
well but it should not
be required in my opinion.


Understandable. I'm curious if other patterns are useful in certain situations, like DSC? Other than that, knowing that the DSI and PHY is correct is good enough for us.


Kind regards,
Marijn

+	DBG("Cmd test pattern setup done\n");
+}
[...]


Thanks!
Marijn



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