Re: [PATCH v2 03/13] arm64: dts: qcom: sdm845: Fix the base addresses of LLCC banks

Manivannan Sadhasivam
2022-12-13T17:14:12Z

On Tue, Dec 13, 2022 at 05:27:45PM +0100, Krzysztof Kozlowski wrote:
> On 12/12/2022 13:33, Manivannan Sadhasivam wrote:
> > The LLCC block has several banks each with a different base address
> > and holes in between. So it is not a correct approach to cover these
> > banks with a single offset/size. Instead, the individual bank's base
> > address needs to be specified in devicetree with the exact size.
> >
> > Also, let's get rid of reg-names property as it is not needed anymore.
> > The driver is expected to parse the reg field based on index to get the
> > addresses of each LLCC banks.
> >
> > Cc: <stable@vger.kernel.org> # 5.4
>
> No, you cannot backport it. You will break users.
>

If the driver change gets backported, it will break users, isn't it?

> > Fixes: ba0411ddd133 ("arm64: dts: sdm845: Add device node for Last level cache controller")
> > Reported-by: Parikshit Pareek <quic_ppareek@quicinc.com>
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > ---
> > arch/arm64/boot/dts/qcom/sdm845.dtsi | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/boot/dts/qcom/sdm845.dtsi b/arch/arm64/boot/dts/qcom/sdm845.dtsi
> > index 65032b94b46d..683b861e060d 100644
> > --- a/arch/arm64/boot/dts/qcom/sdm845.dtsi
> > +++ b/arch/arm64/boot/dts/qcom/sdm845.dtsi
> > @@ -2132,8 +2132,9 @@ uart15: serial@a9c000 {
> >
> > llcc: system-cache-controller@1100000 {
> > compatible = "qcom,sdm845-llcc";
> > - reg = <0 0x01100000 0 0x31000>, <0 0x01300000 0 0x50000>;
> > - reg-names = "llcc_base", "llcc_broadcast_base";
>
> Once property was made required, you cannot remove it. What if other
> bindings user depends on it?
>
> Please instead keep/update the reg-names and/or mark it as deprecated.
> It must stay in DTS for some time.
>

Fair enough. I will mark it as deprecated in binding and will keep it in dts.

Thanks,
Mani

> Best regards,
> Krzysztof
>

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