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

[Xing Zheng]

Hi Doug,

On 2016å06æ13æ 11:10, Xing Zheng wrote:
> Hi Doug,
>
> On 2016å06æ13æ 05:32, Doug Anderson wrote:
> > Xing,
> >
> > On Sun, Jun 12, 2016 at 2:48 AM, Xing 
> > Zheng<zhengxing@xxxxxxxxxxxxxx>  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<ykk@xxxxxxxxxxxxxx>
> > > Signed-off-by: Yakir Yang<ykk@xxxxxxxxxxxxxx>
> > > Signed-off-by: Brian Norris<briannorris@xxxxxxxxxxxx>
> > > Signed-off-by: Xing Zheng<zhengxing@xxxxxxxxxxxxxx>
> > > ---
> > >
> > >   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