linux-kernel - Re: [PATCH V2] cpufreq: imx6q: Only disabling 792MHz OPP for i.MX6ULL types below 792MHz

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Date:   Thu, 23 Nov 2023 12:58:40 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Christoph Niedermaier <cniedermaier@...electronics.com>
Cc:     linux-arm-kernel@...ts.infradead.org,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Sébastien Szymanski 
        <sebastien.szymanski@...adeus.com>, Stefan Agner <stefan@...er.ch>,
        Shawn Guo <shawnguo@...nel.org>, Marek Vasut <marex@...x.de>,
        Fabio Estevam <festevam@...x.de>,
        NXP Linux Team <linux-imx@....com>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2] cpufreq: imx6q: Only disabling 792MHz OPP for
 i.MX6ULL types below 792MHz

On 22-11-23, 14:41, Christoph Niedermaier wrote:
> For a 900MHz i.MX6ULL CPU the 792MHz OPP is disabled. There is no
> convincing reason to disable this OPP. If a CPU can run at 900MHz,
> it should also be able to cope with 792MHz. Looking at the voltage
> level of 792MHz in [1] (page 24, table 10. "Operating Ranges") the
> current defined OPP is above the minimum. So the voltage level
> shouldn't be a problem. However in [2] (page 24, table 10.
> "Operating Ranges"), it is not mentioned that 792MHz OPP isn't
> allowed. Change it to only disable 792MHz OPP for i.MX6ULL types
> below 792 MHz.
> 
> [1] https://www.nxp.com/docs/en/data-sheet/IMX6ULLIEC.pdf
> [2] https://www.nxp.com/docs/en/data-sheet/IMX6ULLCEC.pdf
> 
> Fixes: 0aa9abd4c212 ("cpufreq: imx6q: check speed grades for i.MX6ULL")
> Signed-off-by: Christoph Niedermaier <cniedermaier@...electronics.com>
> Reviewed-by: Marek Vasut <marex@...x.de>
> Reviewed-by: Fabio Estevam <festevam@...x.de>
> ---
> V2: - Improve the commit message
>     - Add Fixes tag
>     - Add Reviewed-by tag
> ---
> Cc: Viresh Kumar <viresh.kumar@...aro.org>
> Cc: "Rafael J. Wysocki" <rafael@...nel.org>
> Cc: Sébastien Szymanski <sebastien.szymanski@...adeus.com>
> Cc: Stefan Agner <stefan@...er.ch>
> Cc: Shawn Guo <shawnguo@...nel.org>
> Cc: Marek Vasut <marex@...x.de>
> Cc: Fabio Estevam <festevam@...x.de>
> Cc: NXP Linux Team <linux-imx@....com>
> Cc: linux-pm@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> To: linux-arm-kernel@...ts.infradead.org
> ---
>  drivers/cpufreq/imx6q-cpufreq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/imx6q-cpufreq.c b/drivers/cpufreq/imx6q-cpufreq.c
> index 494d044b9e72..33728c242f66 100644
> --- a/drivers/cpufreq/imx6q-cpufreq.c
> +++ b/drivers/cpufreq/imx6q-cpufreq.c
> @@ -327,7 +327,7 @@ static int imx6ul_opp_check_speed_grading(struct device *dev)
>  			imx6x_disable_freq_in_opp(dev, 696000000);
>  
>  	if (of_machine_is_compatible("fsl,imx6ull")) {
> -		if (val != OCOTP_CFG3_6ULL_SPEED_792MHZ)
> +		if (val < OCOTP_CFG3_6ULL_SPEED_792MHZ)
>  			imx6x_disable_freq_in_opp(dev, 792000000);
>  
>  		if (val != OCOTP_CFG3_6ULL_SPEED_900MHZ)

What about another similar check ?

		if (val != OCOTP_CFG3_6ULL_SPEED_900MHZ)

-- 
viresh