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 13:03:07 +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 23-11-23, 12:58, Viresh Kumar wrote:
> 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)

Yeah, that isn't required I guess.

Applied. Thanks.

-- 
viresh