Re: [PATCH] clk: imx6ull: use OSC clock during AXI rate change

[Stefan Agner]

On 08.05.2018 09:32, Jacky Bai wrote:
>> Subject: Re: [PATCH] clk: imx6ull: use OSC clock during AXI rate change
>>
>> Hi Jacky,
>>
>> On 02.05.2018 09:38, Shawn Guo wrote:
>> > Hi Jacky,
>> >
>> > Do you see this problem on i.MX6 ULL?  What's your take on Stefan's fix?
>>
>> Any comment to this?
>>
>> It is 4.17.0-rc4 is out and i.MX 6ULL is still broken :-(
>>
> Hi Stefan,
> 
> I have tried two 6ULL board, I don't meet such issue. System can boot
> up successfully with commit 6f9575e55632 included.
> Anyway, the change in this patch is ok for me. it is no harm to the
> BUS clock change flow.

Hm, that is interesting, maybe it is because we use a different SKU? Or
maybe bootloader?

I tested here with a 800 MHz clocked variant on a Colibri iMX6ULL using
U-Boot 2016.11.

--
Stefan

> 
> Jacky
>> --
>> Stefan
>>
>> >
>> > Shawn
>> >
>> > On Wed, Apr 18, 2018 at 02:49:08PM +0200, Stefan Agner wrote:
>> >> On i.MX6 ULL using PLL3 seems to cause a freeze when setting the
>> >> parent to IMX6UL_CLK_PLL3_USB_OTG. This only seems to appear since
>> >> commit 6f9575e55632 ("clk: imx: Add CLK_IS_CRITICAL flag for busy
>> >> divider and busy mux"), probably because the clock is now forced to
>> >> be on.
>> >>
>> >> Fixes: 6f9575e55632("clk: imx: Add CLK_IS_CRITICAL flag for busy
>> >> divider and busy mux")
>> >> Signed-off-by: Stefan Agner <stefan@xxxxxxxx>
>> >> ---
>> >> This addresses a regression ssen on v4.17-rc1 where the kernel boots
>> >> during clock initialization, see also:
>> >>
>> https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpa
>> >>
>> tchwork.kernel.org%2Fpatch%2F10295927%2F&data=02%7C01%7Cping.bai%
>> 40nx
>> >>
>> p.com%7C023287ec65034c4db45f08d5b419effb%7C686ea1d3bc2b4c6fa92cd9
>> 9c5c
>> >>
>> 301635%7C0%7C0%7C636612945852594725&sdata=U0ZGid9ZBey0FXfId2dhZb
>> hVl8p
>> >> CcjTiexG3JHYwCA4%3D&reserved=0
>> >>
>> >>  drivers/clk/imx/clk-imx6ul.c | 2 +-
>> >>  1 file changed, 1 insertion(+), 1 deletion(-)
>> >>
>> >> diff --git a/drivers/clk/imx/clk-imx6ul.c
>> >> b/drivers/clk/imx/clk-imx6ul.c index 114ecbb94ec5..12320118f8de
>> >> 100644
>> >> --- a/drivers/clk/imx/clk-imx6ul.c
>> >> +++ b/drivers/clk/imx/clk-imx6ul.c
>> >> @@ -464,7 +464,7 @@ static void __init imx6ul_clocks_init(struct
>> device_node *ccm_node)
>> >>  	clk_set_rate(clks[IMX6UL_CLK_AHB], 99000000);
>> >>
>> >>  	/* Change periph_pre clock to pll2_bus to adjust AXI rate to 264MHz
>> */
>> >> -	clk_set_parent(clks[IMX6UL_CLK_PERIPH_CLK2_SEL],
>> clks[IMX6UL_CLK_PLL3_USB_OTG]);
>> >> +	clk_set_parent(clks[IMX6UL_CLK_PERIPH_CLK2_SEL],
>> >> +clks[IMX6UL_CLK_OSC]);
>> >>  	clk_set_parent(clks[IMX6UL_CLK_PERIPH],
>> clks[IMX6UL_CLK_PERIPH_CLK2]);
>> >>  	clk_set_parent(clks[IMX6UL_CLK_PERIPH_PRE],
>> clks[IMX6UL_CLK_PLL2_BUS]);
>> >>  	clk_set_parent(clks[IMX6UL_CLK_PERIPH],
>> >> clks[IMX6UL_CLK_PERIPH_PRE]);
>> >> --
>> >> 2.17.0
>> >>