Re: [PATCH 33/33] ARM: i.MX6: implement clocks using common clock framework

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On Thu, Apr 26, 2012 at 02:57:02PM +0800, Richard Zhao wrote:
> On Thu, Apr 26, 2012 at 08:41:50AM +0200, Sascha Hauer wrote:
> > On Thu, Apr 26, 2012 at 10:48:38AM +0800, Richard Zhao wrote:
> > > The below code is removed from mx6q_clocks_init implicitly.
> > > Why? If it's reasonable, it needs to be on a separate patch too.
> > > 
> > > /* only keep necessary clocks on */
> > > writel_relaxed(0x3 << CG0  | 0x3 << CG1  | 0x3 << CG2,  CCGR0);
> > > writel_relaxed(0x3 << CG8  | 0x3 << CG9  | 0x3 << CG10, CCGR2);
> > > writel_relaxed(0x3 << CG10 | 0x3 << CG12,               CCGR3);
> > > writel_relaxed(0x3 << CG4  | 0x3 << CG6  | 0x3 << CG7,  CCGR4);
> > > writel_relaxed(0x3 << CG0,                              CCGR5);
> > > writel_relaxed(0,                                       CCGR6);
> > > writel_relaxed(0,                                       CCGR7);
> > 
> > The clock framework will turn them off automatically.
> > For the first time the hardware state will be consistent with the
> > software state. Hurray!
> > 
> > > 
> > > clk_enable(&uart_clk);
> > 
> > This is not needed anymore. For the early debug case we depend on the
> > uart being enabled by the bootloader anyway, so it's safe to assume that
> > the clock is turned on also. Otherwise the uart driver turns on this
> > clock when needed.
> > 
> > > clk_enable(&mmdc_ch0_axi_clk);
> > 
> > This reminds me on something. This clock is turned on in the loop around
> > clks_init_on. Since we now have pointers to each clock we don't need the
> > clk_get_sys() anymore but can use the pointers directly. Will fix this
> > one.
> > 
> > > 
> > > clk_set_rate(&pll4_audio, FREQ_650M);
> > > clk_set_rate(&pll5_video, FREQ_650M);
> > > clk_set_parent(&ipu1_di0_clk, &ipu1_di0_pre_clk);
> > > clk_set_parent(&ipu1_di0_pre_clk, &pll5_video);
> > > clk_set_parent(&gpu3d_shader_clk, &pll2_pfd_594m);
> > > clk_set_rate(&gpu3d_shader_clk, FREQ_594M);
> > > clk_set_parent(&gpu3d_core_clk, &mmdc_ch0_axi_clk);
> > > clk_set_rate(&gpu3d_core_clk, FREQ_528M);
> > > clk_set_parent(&asrc_serial_clk, &pll3_usb_otg);
> > > clk_set_rate(&asrc_serial_clk, 1500000);
> > > clk_set_rate(&enfc_clk, 11000000);
> > > 
> > > /*
> > >  * Before pinctrl API is available, we have to rely on the pad
> > >  * configuration set up by bootloader.  For usdhc example here,
> > >  * u-boot sets up the pads for 49.5 MHz case, and we have to lower
> > >  * the usdhc clock from 198 to 49.5 MHz to match the pad configuration.
> > >  *
> > >  * FIXME: This is should be removed after pinctrl API is available.
> > >  * At that time, usdhc driver can call pinctrl API to change pad
> > >  * configuration dynamically per different usdhc clock settings.
> > >  */
> > > clk_set_rate(&usdhc1_clk, 49500000);
> > > clk_set_rate(&usdhc2_clk, 49500000);
> > > clk_set_rate(&usdhc3_clk, 49500000);
> > > clk_set_rate(&usdhc4_clk, 49500000);
> > 
> > Can't say anything to these, probably Shawn has simply lost them while
> > porting.
> > 
> > > 
> > > clk_set_parent(&cko1_clk, &ahb_clk);
> > 
> > Why this? The cko pin has different usecases on each board, mostly I
> > think for debugging. We shouldn't touch it here.
> clko1's used by audio codec on many boards.

How many?  Even it's truly so many, it's still board specific lookup,
which I do not want to have in soc specific clock driver.

> Do you/Shawn think I can add board specific code here with
> of_machine_is_compatible?

No, I do not think so.

> I need to add audio codec clkdev. Other places
> can not get clk pointers.
> 
As what I have been told you, I would rather you have a generic lookup
for cko in clk-imx6q.c, and then you can get the clk pointer at wherever
you should add board specific lookup for the clk.  That generic lookup
could be used by whatever boards for whatever purpose without messing
up clk-imx6q.c.

-- 
Regards,
Shawn

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