Re: [PATCH 19/20] OMAPDSS: DSI: fix DSI channel source initialization

[Tomi Valkeinen <tomi.valkeinen@ti.com>]

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On 2013-03-11 10:15, Archit Taneja wrote:
> On Monday 11 March 2013 12:32 PM, Tomi Valkeinen wrote:
>> On 2013-03-11 08:10, Archit Taneja wrote:
>>> Hi,
>>>
>>> On Friday 08 March 2013 05:21 PM, Tomi Valkeinen wrote:
>>>> During the initialization of the DSI protocol registers, we always set
>>>> the sources of all DSI channels to L4. However, we don't update the
>>>> value in the dsi_data, so we may end up with a different value in the
>>>> register and in the dsi_data, leading to DSI problems.
>>>>
>>>> This patch fixes the issue by initializing also the channel source in
>>>> the dsi_data.
>>>
>>> We set in omap_dsihw_probe:
>>>
>>> static int __init omap_dsihw_probe(struct platform_device *dsidev)
>>> {
>>>      ...
>>>      ...
>>>          /* DSI VCs initialization */
>>>          for (i = 0; i < ARRAY_SIZE(dsi->vc); i++) {
>>>                  dsi->vc[i].source = DSI_VC_SOURCE_L4;
>>>                  dsi->vc[i].dssdev = NULL;
>>>                  dsi->vc[i].vc_id = 0;
>>>          }
>>>      ...
>>>      ...
>>> }
>>
>> Hmm... I did have a bug related to this when prototyping CDF. Ah.
>> Consider this:
>>
>> Panel powers up and uses DSI normally. A DSI VC is set to video mode.
>> Then the panel power down. Then it powers up again, and enables DSI. At
>> this time, dsi_vc_initial_config() is called again, setting the source
>> in the registers to L4. But the source in dsi_data is still VP.
> 
> Oh ok.
> 
>>
>> So perhaps the whole piece of code from omap_dsihw_probe should be moved
>> to somewhere else (dsi_vc_initial_config() sounds like a good place), so
>> that they are initialized each time the registers are initialized.
> 
> VC source is something which seems fine to do in
> dsi_vc_initial_config(). I'm not sure about the dssdev and vc_id fields
> though, we would need to call omap_dsi_request_vc() and
> omap_dsi_set_vc_id() again after a power off. Currently, we do it only
> once in taal_probe().

Oh, right. Well, neither dssdev nor vc_id is written to registers, so
they won't have similar issues in any case. So I guess this patch is
fine as it is, and we do not need to touch dssdev nor vc_id.

 Tomi



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