On 23-09-04, Ahmad Fatoum wrote:
> This is a port of Linux commit 9f4c8f9607c3147d291b70c13dd01c738ed41faf:
>
> | Author: Anson Huang <anson.huang@xxxxxxx>
> | AuthorDate: Wed Dec 19 05:24:58 2018 +0000
> | Commit: Thierry Reding <thierry.reding@xxxxxxxxx>
> | CommitDate: Mon Dec 24 12:06:56 2018 +0100
> |
> | pwm: imx: Add ipg clock operation
> |
> | i.MX PWM module's ipg_clk_s is for PWM register access, on most of i.MX
> | SoCs, this ipg_clk_s is from system ipg clock or perclk which is always
> | enabled, but on i.MX7D, the ipg_clk_s is from PWM1_CLK_ROOT which is
> | controlled by CCGR132, that means the CCGR132 MUST be enabled first
> | before accessing PWM registers on i.MX7D. This patch adds ipg clock
> | operation to make sure register access successfully on i.MX7D and it
> | fixes Linux kernel boot up hang during PWM driver probe.
> |
> | Fixes: 4a23e6ee9f69 ("ARM: dts: imx7d-sdb: Restore pwm backlight support")
> | Signed-off-by: Anson Huang <Anson.Huang@xxxxxxx>
> | Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxx>
>
> Unlike the Linux version, we make clk_ipg optional to reduce changes for
> older SoCs.
>
> This fixes system hang during PWM access on i.MX8M and presumably i.MX7.
>
> Reported-by: Bastian Krause <bst@xxxxxxxxxxxxxx>
> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
Reviewed-by: Marco Felsch <m.felsch@xxxxxxxxxxxxxx>
