linux-kernel - Re: [PATCH] clk: imx: lpcg: write twice when writing lpcg regs

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Date:   Mon, 9 Sep 2019 19:51:12 +0800
From:   Dong Aisheng <dongas86@...il.com>
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     "festevam@...il.com" <festevam@...il.com>,
        "mturquette@...libre.com" <mturquette@...libre.com>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        Aisheng Dong <aisheng.dong@....com>,
        Peng Fan <peng.fan@....com>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        dl-linux-imx <linux-imx@....com>,
        Anson Huang <anson.huang@....com>,
        Jacky Bai <ping.bai@....com>, Abel Vesa <abel.vesa@....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@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] clk: imx: lpcg: write twice when writing lpcg regs

On Sat, Sep 7, 2019 at 9:47 PM Stephen Boyd <sboyd@...nel.org> wrote:
>
> Quoting Peng Fan (2019-08-27 01:17:50)
> > From: Peng Fan <peng.fan@....com>
> >
> > There is hardware issue that:
> > The output clock the LPCG cell will not turn back on as expected,
> > even though a read of the IPG registers in the LPCG indicates that
> > the clock should be enabled.
> >
> > The software workaround is to write twice to enable the LPCG clock
> > output.
> >
> > Signed-off-by: Peng Fan <peng.fan@....com>
>
> Does this need a Fixes tag?

Not sure as it's not code logic issue but a hardware bug.
And 4.19 LTS still have not this driver support.

Regards
Aisheng

>