linux-kernel - Re: [PATCH] clk: qcom: gcc-sdm845: Use floor ops for sdcc clks

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Message-ID: <5d6eed69.1c69fb81.b7ca5.7345@mx.google.com>
Date:   Tue, 03 Sep 2019 15:47:04 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Doug Anderson <dianders@...omium.org>,
        Taniya Das <tdas@...eaurora.org>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH] clk: qcom: gcc-sdm845: Use floor ops for sdcc clks

Quoting Taniya Das (2019-09-03 08:52:12)
> Hi,
> 
> On 8/31/2019 3:04 AM, Doug Anderson wrote:
> > Hi,
> > 
> > On Fri, Aug 30, 2019 at 12:51 PM Stephen Boyd <swboyd@...omium.org> wrote:
> >>
> >> Some MMC cards fail to enumerate properly when inserted into an MMC slot
> >> on sdm845 devices. This is because the clk ops for qcom clks round the
> >> frequency up to the nearest rate instead of down to the nearest rate.
> >> For example, the MMC driver requests a frequency of 52MHz from
> >> clk_set_rate() but the qcom implementation for these clks rounds 52MHz
> >> up to the next supported frequency of 100MHz. The MMC driver could be
> >> modified to request clk rate ranges but for now we can fix this in the
> >> clk driver by changing the rounding policy for this clk to be round down
> >> instead of round up.
> > 
> > Since all the MMC rates are expressed as "maximum" clock rates doing
> > it like you are doing it now seems sane.
> > 
> > 
> 
> Looks like we need to update/track it for all SDCC clocks for all targets.
> 

Yeah. It would be great if you can send the patches. Otherwise I'll
throw it on my todo list named 'forever'.