linux-kernel - Re: [PATCH] arm64: dts: qcom: sdm845-db845c: Mark cont splash memory region as reserved

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Date:   Thu, 9 Feb 2023 14:35:07 +0530
From:   Amit Pundir <amit.pundir@...aro.org>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        "Bryan O'Donoghue" <bryan.odonoghue@...aro.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Caleb Connolly <caleb.connolly@...aro.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        dt <devicetree@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arm64: dts: qcom: sdm845-db845c: Mark cont splash memory
 region as reserved

On Tue, 31 Jan 2023 at 19:03, Dmitry Baryshkov
<dmitry.baryshkov@...aro.org> wrote:
>
> On 31/01/2023 14:45, Konrad Dybcio wrote:
> >
> >
> > On 31.01.2023 12:06, Dmitry Baryshkov wrote:
> >> On Tue, 31 Jan 2023 at 12:54, Bryan O'Donoghue
> >> <bryan.odonoghue@...aro.org> wrote:
> >>>
> >>> On 24/01/2023 18:28, Amit Pundir wrote:
> >>>> Put cont splash memory region under the reserved-memory
> >>>> as confirmed by the downstream code as well.
> >>>>
> >>>> Signed-off-by: Amit Pundir <amit.pundir@...aro.org>
> >>>> ---
> >>>>    arch/arm64/boot/dts/qcom/sdm845-db845c.dts | 8 ++++++++
> >>>>    1 file changed, 8 insertions(+)
> >>>>
> >>>> diff --git a/arch/arm64/boot/dts/qcom/sdm845-db845c.dts b/arch/arm64/boot/dts/qcom/sdm845-db845c.dts
> >>>> index f41c6d600ea8..2ae59432cbda 100644
> >>>> --- a/arch/arm64/boot/dts/qcom/sdm845-db845c.dts
> >>>> +++ b/arch/arm64/boot/dts/qcom/sdm845-db845c.dts
> >>>> @@ -100,6 +100,14 @@ hdmi_con: endpoint {
> >>>>                };
> >>>>        };
> >>>>
> >>>> +     reserved-memory {
> >>>> +             /* Cont splash region set up by the bootloader */
> >>>> +             cont_splash_mem: framebuffer@...00000 {
> >>>> +                     reg = <0x0 0x9d400000 0x0 0x2400000>;
> >>>> +                     no-map;
> >>>> +             };
> >>>> +     };
> >>>> +
> >>>>        lt9611_1v8: lt9611-vdd18-regulator {
> >>>>                compatible = "regulator-fixed";
> >>>>                regulator-name = "LT9611_1V8";
> >>>
> >>> Doesn't this mean we loose 0x2400000 of DRAM for all rb3 platforms
> >>> though ? About what 37 megabytes.. ?
> >>
> >> I think this memory is further used for display memory allocation. So
> >> we are not loosing it, but dedicating it to the framebuffer memory.
> > Not exactly, to do so, you'd have to use the memory-region property
> > with mdss, which nobody does. Otherwise it's just a hole for Linux.
>
> Then maybe it's time to start using that property?

Hi, So what is the verdict on this patch?

I submitted this fix to make sure UFS don't map and crash on it, which
I have seen happening occassionaly on db845c and Caleb reported
similar issues on his sdm845 device iirc. I should have probably put
that in my commit message as well.

Regards,
Amit Pundir

>
> >
> > Konrad
> >>
> >>
>
> --
> With best wishes
> Dmitry
>