linux-kernel - Re: [PATCH v5 4/4] soc: imx8m: change to use platform driver

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Date:   Mon, 23 Nov 2020 17:58:58 +0100
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Alice Guo <alice.guo@....com>
Cc:     robh+dt@...nel.org, shawnguo@...nel.org, s.hauer@...gutronix.de,
        linux-imx@....com, peng.fan@....com, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v5 4/4] soc: imx8m: change to use platform driver

On Mon, Nov 23, 2020 at 05:51:08PM +0800, Alice Guo wrote:
> Directly reading ocotp register depends on that bootloader enables ocotp
> clk, which is not always effective, so change to use nvmem API. Using
> nvmem API requires to support driver defer probe and thus change
> soc-imx8m.c to use platform driver.
> 
> The other reason is that directly reading ocotp register causes kexec
> kernel hang because the 1st kernel running will disable unused clks
> after kernel boots up, and then ocotp clk will be disabled even if
> bootloader enables it. When kexec kernel, ocotp clk needs to be enabled
> before reading ocotp registers, and nvmem API with platform driver
> supported can accomplish this.
> 
> Signed-off-by: Alice Guo <alice.guo@....com>
> ---
> 

Reviewed-by: Krzysztof Kozlowski <krzk@...nel.org>

Best regards,
Krzysztof