On 07/13/2018 11:06 AM, Anson Huang wrote:
[...]
>>
>> On 07/13/2018 10:54 AM, Anson Huang wrote:
>>> As display power domain is combined with lcdif node on some i.MX
>>> platforms like i.MX6SL, when lcdif driver is enabled, the mxsfb_load
>>> is called to enable runtime pm, and a pair of pm_runtime_get_sync and
>>> pm_runtime_put_sync are also called, that will cause generic power
>>> domain driver to disable lcdif power domain and lcdif is no longer
>>> working, the lcdif power should ONLY be turned off when display is
>>> disabled, so move the pm_runtime_put_sync to mxsfb_unload and remove
>>> the pm_runtime_get_sync in mxsfb_unload as well, in this way, when
>>> display is enabled, the lcdif power will be always ON until the
>>> display is disabled.
>>>
>>> Signed-off-by: Anson Huang <Anson.Huang@xxxxxxx>
>>
>> Doesn't this also mean the block will always be on, thus wasting power ?
>
> I think drm driver should have somewhere to implement the display
> disable case, like when fb0 is blank (echo 1 > /sys/class/graphics/fb0/blank),
Isn't this just the fbdev emulation on top of drm/kms ?
I think this stuff can be compiled out completely.
> then lcdif can be powered gated, and
> when display is back on (unblank), lcdif needs to be re-initialization and display will
> be on, current implementation is incorrect, with kernel booting up, lcdif
> is NOT working at all.
It works fine on MX6SX , so I think this is isolated to MX6SL ?
I'm CCing Stefan, he might have some valuable feedback here.
> The runtime power gating case can be implemented later to save power,
> need lcdif experts to do it. Thanks.
>
> Anson.
>
>>
>>> ---
>>> drivers/gpu/drm/mxsfb/mxsfb_drv.c | 3 +--
>>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.c
>>> b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
>>> index ffe5137..1ba179b 100644
>>> --- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c
>>> +++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
>>> @@ -235,7 +235,6 @@ static int mxsfb_load(struct drm_device *drm,
>>> unsigned long flags)
>>>
>>> pm_runtime_get_sync(drm->dev);
>>> ret = drm_irq_install(drm, platform_get_irq(pdev, 0));
>>> - pm_runtime_put_sync(drm->dev);
>>>
>>> if (ret < 0) {
>>> dev_err(drm->dev, "Failed to install IRQ handler\n"); @@ -264,6
>>> +263,7 @@ static int mxsfb_load(struct drm_device *drm, unsigned long
>>> flags)
>>> err_irq:
>>> drm_panel_detach(mxsfb->panel);
>>> err_vblank:
>>> + pm_runtime_put_sync(drm->dev);
>>> pm_runtime_disable(drm->dev);
>>>
>>> return ret;
>>> @@ -279,7 +279,6 @@ static void mxsfb_unload(struct drm_device *drm)
>>> drm_kms_helper_poll_fini(drm);
>>> drm_mode_config_cleanup(drm);
>>>
>>> - pm_runtime_get_sync(drm->dev);
>>> drm_irq_uninstall(drm);
>>> pm_runtime_put_sync(drm->dev);
>>>
>>>
>>
>>
>> --
>> Best regards,
>> Marek Vasut
--
Best regards,
Marek Vasut
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