[Intel-gfx] [PATCH resend 05/15] drm/i915/dsi: Document the panel enable / disable sequences from the spec

[Hans de Goede]

Hi Bob,

Thank you for the review of this patch-set.

On 24-02-17 18:00, Bob Paauwe wrote:
> On Mon, 20 Feb 2017 15:08:35 +0100
> Hans de Goede <hdegoede at redhat.com> wrote:
>
>> Document the DSI panel enable / disable sequences from the spec,
>> for easy comparison between the code and the spec.
>>
>> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
>> Acked-by: Jani Nikula <jani.nikula at intel.com>
>> ---
>>  drivers/gpu/drm/i915/intel_dsi.c | 68 ++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 68 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
>> index 072f99b..8808f87 100644
>> --- a/drivers/gpu/drm/i915/intel_dsi.c
>> +++ b/drivers/gpu/drm/i915/intel_dsi.c
>> @@ -552,6 +552,74 @@ static void intel_dsi_prepare(struct intel_encoder *intel_encoder,
>>  			      struct intel_crtc_state *pipe_config);
>>  static void intel_dsi_unprepare(struct intel_encoder *encoder);
>>
>> +/*
>> + * Panel enable/disable sequences from the VBT spec.
>> + *
>> + * Note the spec has AssertReset / DeassertReset swapped from their
>> + * usual naming. We use the normal names to avoid confusion (so below
>> + * they are swapped compared to the spec).
>> + *
>> + * v2 sequence for video mode:
>> + * - power on
>> + * - wait t1+t2
>> + * - MIPIDeassertResetPin
>> + * - clk/data lines to lp-11
>> + * - MIPISendInitialDcsCmds
>> + * - turn on DPI
>> + * - MIPIDisplayOn
>> + * - wait t5
>> + * - backlight on
>> + * ...
>> + * - backlight off
>> + * - wait t6
>> + * - MIPIDisplayOff
>> + * - turn off DPI
>> + * - clk/data lines to lp-00
>> + * - MIPIAssertResetPin
>> + * - wait t3
>> + * - power off
>> + * - wait t4
>> + *
>> + * v3 sequence for video mode:
>> + * - MIPIPanelPowerOn
>> + * - MIPIDeassertResetPin
>> + * - set clk/data lines to lp-11
>> + * - MIPISendInitialDcsCmds (LP)
>> + * - turn on DPI
>> + * - MIPITearOn (command mode only) + MIPIDisplayOn (LP and HS)
>
> What does (command mode only) mean in the video mode sequence?  My
> assumption is that TearOn is only used in command mode, and as such,
> shouldn't be done in video mode.  Is that wrong?

I don't know I don't have access to the VBT spec I merely copied
the contents of the comment this is adding from a mail which contained
the sequences extracted from the doc by someone at Intel (Jani IIRC).

>
>> + * - MIPIBacklightOn
>
> What's the difference between MIPIBacklightOn here and "backlight on"
> in the v2 sequence?

AFAICT there is none, again copy pasted from the mail as is.

> It might be cleaner to make this a table with V2 and V3 as columns,
> that would also help to highlight the differences in the two versions.
> Maybe even put the command mode sequence in a third column if it
> doesn't make the lines too long.

I can try once we've cleared up the other bits.

>> + * ...
>> + * - MIPIBacklightOff
>> + * - turn off DPI
>> + * - MIPITearOff + MIPIDisplayOff (LP)
>> + * - clk/data lines to lp-00
>> + * - MIPIAssertResetPin
>> + * - MIPIPanelPowerOff
>> + *
>> + * sequence for command mode:
>
> Is this the sequence for both V2 and V3 or only V3?

I think command mode is V3 only, but I'm not sure. I only have
access to video mode devices myself.

>> + * - power on
>> + * - wait t1+t2
>> + * - MIPIDeassertResetPin
>> + * - clk/data lines to lp-11
>> + * - MIPISendInitialDcsCmds
>> + * - MIPITearOn
>> + * - MIPIDisplayOn
>> + * - set pipe to dsr mode
>> + * - wait t5
>> + * - backlight on
>> + * ... issue write_mem_start/write_mem_continue commands ...
>> + * - backlight off
>> + * - wait t6
>> + * - disable pipe dsr mode
>> + * - MIPITearOff
>> + * - MIPIDisplayOff
>> + * - clk/data lines to lp-00
>> + * - MIPIAssertResetPin
>> + * - wait t3
>> + * - power off
>> + * - wait t4
>> + */
>> +
>>  static void intel_dsi_pre_enable(struct intel_encoder *encoder,
>>  				 struct intel_crtc_state *pipe_config,
>>  				 struct drm_connector_state *conn_state)
>
>
>

Regards,

Hans