linux-kernel - Re: [PATCH] clk: imx8mq: Mark AHB clock as critical

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Date:   Sat, 27 Jul 2019 09:30:57 +0300
From:   Daniel Baluta <daniel.baluta@...il.com>
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     Abel Vesa <abel.vesa@....com>, Anson Huang <anson.huang@....com>,
        Fabio Estevam <fabio.estevam@....com>,
        Mike Turquette <mturquette@...libre.com>,
        Sascha Hauer <kernel@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>,
        dl-linux-imx <linux-imx@....com>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] clk: imx8mq: Mark AHB clock as critical

On Tue, Jul 23, 2019 at 6:17 AM Stephen Boyd <sboyd@...nel.org> wrote:
>
> Quoting Abel Vesa (2019-07-05 01:52:19)
> > On 19-06-25 15:32:22, Stephen Boyd wrote:
> > > Quoting Abel Vesa (2019-06-25 02:01:56)
> > > > Keep the AHB clock always on since there is no driver to control it and
> > > > all the other clocks that use it as parent rely on it being always enabled.
> > > >
> > > > Signed-off-by: Abel Vesa <abel.vesa@....com>
> > > > ---
> > > >  drivers/clk/imx/clk-imx8mq.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/clk/imx/clk-imx8mq.c b/drivers/clk/imx/clk-imx8mq.c
> > > > index 5fbc2a7..b48268b 100644
> > > > --- a/drivers/clk/imx/clk-imx8mq.c
> > > > +++ b/drivers/clk/imx/clk-imx8mq.c
> > > > @@ -398,7 +398,7 @@ static int imx8mq_clocks_probe(struct platform_device *pdev)
> > > >         clks[IMX8MQ_CLK_NOC_APB] = imx8m_clk_composite_critical("noc_apb", imx8mq_noc_apb_sels, base + 0x8d80);
> > > >
> > > >         /* AHB */
> > > > -       clks[IMX8MQ_CLK_AHB] = imx8m_clk_composite("ahb", imx8mq_ahb_sels, base + 0x9000);
> > > > +       clks[IMX8MQ_CLK_AHB] = imx8m_clk_composite_critical("ahb", imx8mq_ahb_sels, base + 0x9000);
> > >
> > > Please add a comment into the code why it's critical.
> >
> > Comment explaining why the AHB bus clock is critical ?
> > Isn't that self-explanatory ?
>
> Nope, it isn't self-explanatory, because nothing on this line says "bus"
> and it could be that someone reading this code isn't well versed in the
> concepts of ARM world AHB to connect the two.

Agree with Stephen. Commit message should try to give as much details
as possible
also maybe educate the readers who might not have that much knowledge.

Abel, I understand that for someone who works daily with this part of the kernel
this change might look trivial.

Also, without this patch linux-next hangs on imx8mq.

With the explanation added you can add my:

Tested-by: Daniel Baluta <daniel.baluta@....com>

thanks,
Daniel.