Subject: [PATCH] clk: rockchip: add pclk_vio_grf to critical clock on the RK3399

From: [email-masked] (Xing Zheng)
Date: Mon, 13 Jun 2016 11:30:22 +0800

Hi Doug,

On 2016?06?13? 11:10, Xing Zheng wrote:
> Hi Doug,
>
> On 2016?06?13? 05:32, Doug Anderson wrote:
>> Xing,
>>
>> On Sun, Jun 12, 2016 at 2:48 AM, Xing 
>> Zheng<[email-masked]>  wrote:
>>> The pclk_vio_grf supply power for GRF IOs, if it is disabled, will
>>> cause abnormal operation of the GRF.
>>>
>>> The clock tree of the pclk_vio like this:
>>>               | --> pclk_vio_grf
>>> ... pclk_vio | --> pclk_mipi_dsi1
>>>               | --> pclk_mipi_dsi0
>>>
>>> and the pclk_mipi_dsi0 and pclk_mipi_dsi1 don't have the flag
>>> CLK_IGNORE_UNUSED, and they will be disabled by clk_disable_unused
>>> when startup:
>>> clk_disable_unused
>>>    --> clk_disable_unprepare
>>>      --> clk_disable
>>>        --> clk_core_disable(core->parent)
>>>
>>> then, the pclk_vio_grf also is disabled. Therefore, we need to add
>>> pclk_vio_grf to critical clock and avoid to disable pclk_vio and
>>> pclk_vio_grf.
>>>
>>> Tested-by: Yakir Yang<[email-masked]>
>>> Signed-off-by: Yakir Yang<[email-masked]>
>>> Signed-off-by: Brian Norris<[email-masked]>
>>> Signed-off-by: Xing Zheng<[email-masked]>
>>> ---
>>>
>>>   drivers/clk/rockchip/clk-rk3399.c |    1 +
>>>   1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/clk/rockchip/clk-rk3399.c 
>>> b/drivers/clk/rockchip/clk-rk3399.c
>>> index b6742fa..7ecb12c3 100644
>>> --- a/drivers/clk/rockchip/clk-rk3399.c
>>> +++ b/drivers/clk/rockchip/clk-rk3399.c
>>> @@ -1485,6 +1485,7 @@ static const char *const 
>>> rk3399_cru_critical_clocks[] __initconst = {
>>>          "gpll_hclk_perilp1_src",
>>>          "gpll_aclk_perilp0_src",
>>>          "gpll_aclk_perihp_src",
>>> +       "pclk_vio_grf",
>> This clock is only needed when doing video output (like eDP), right?
>> That means it is not really a critical clock.  Critical clocks are
>> supposed to be ones that are needed for the basic functioning of the
>> system and that can never be turned off in any circumstances. In this
>> case, if someone were running a rk3399 device and didn't have any
>> video output they would want this clock off.
>>
>> Can you figure out in exactly which circumstances this clock needs to
>> be on and then add a proper consumer of this clock?  For instance, if
>> this clock is needed whenever the VOP is outputting data, then the VOP
>> should be a client and should turn this clock on and off when video is
>> being output.  If this clock is needed whenever you access VOP
>> registers, then the VOP should be a client and turn this clock on
>> around register accesses.
>>
>>
Additional, we are discussing that we should turn the "pclk_vio" on and 
off in
video drivers when the video consumer needs to this clock.

Thanks.

>>
> Yes, the pclk_vio_grf is needed for doing video output.
> andpclk_vio_grf supply for: grf_soc_con9, 20~26, grf_hdcp
>
> From our design folks, we have many GRF registers in different power 
> domains,
> and these GRF gates should be always enabled. In this case, we can 
> avoid some
> of the operations GRF registers exception problems, and it is only a 
> very small
> increase in  power consumption (aboult <=1ma).
>
> I will refer the latest TRM to update a new patch for always enable 
> these GRFs.
>
> Please drop this patch.

-- 
- Xing Zheng