Re: [PATCH v2 00/13] Qcom: LLCC/EDAC: Fix base address used for LLCC banks

[Andrew Halaney]

On Tue, Dec 13, 2022 at 10:58:02AM +0530, Manivannan Sadhasivam wrote:
> On Mon, Dec 12, 2022 at 01:23:40PM -0600, Andrew Halaney wrote:
> > On Mon, Dec 12, 2022 at 06:02:58PM +0530, Manivannan Sadhasivam wrote:
> > > The Qualcomm LLCC/EDAC drivers were using a fixed register stride for
> > > accessing the (Control and Status Regsiters) CSRs of each LLCC bank.
> > > This offset only works for some SoCs like SDM845 for which driver support
> > > was initially added.
> > >
> > > But the later SoCs use different register stride that vary between the
> > > banks with holes in-between. So it is not possible to use a single register
> > > stride for accessing the CSRs of each bank. By doing so could result in a
> > > crash with the current drivers. So far this crash is not reported since
> > > EDAC_QCOM driver is not enabled in ARM64 defconfig and no one tested the
> > > driver extensively by triggering the EDAC IRQ (that's where each bank
> > > CSRs are accessed).
> > >
> > > For fixing this issue, let's obtain the base address of each LLCC bank from
> > > devicetree and get rid of the fixed stride.
> > >
> > > This series affects multiple platforms but I have only tested this on
> > > SM8250 and SM8450. Testing on other platforms is welcomed.
> > >
> > 
> > Tested-by: Andrew Halaney <ahalaney@xxxxxxxxxx> # sa8540p-ride
> > 
> 
> Thanks!
> 
> > I took this for a quick spin on the qdrive3 I've got access to without
> > any issue:
> > 
> >     [root@localhost ~]# modprobe qcom_edac
> >     [root@localhost ~]# dmesg | grep -i edac
> >     [    0.620723] EDAC MC: Ver: 3.0.0
> >     [    1.165417] ghes_edac: GHES probing device list is empty
> >     [  594.688103] EDAC DEVICE0: Giving out device to module qcom_llcc_edac controller llcc: DEV qcom_llcc_edac (INTERRUPT)
> >     [root@localhost ~]# cat /proc/interrupts | grep ecc
> >     174:          0          0          0          0          0          0          0          0     GICv3 614 Level     llcc_ecc
> >     [root@localhost ~]#
> > 
> > Potentially stupid question, but are users expected to manually load the
> > driver as I did? I don't see how it would be loaded automatically in the
> > current state, but thought it was funny that I needed to modprobe
> > myself.
> > 
> > Please let me know if you want me to do any more further testing!
> > 
> 
> Well, I always ended up using the driver as a built-in. I do make it module for
> build test but never really used it as a module, so didn't catch this issue.
> 
> This is due to the module alias not exported by the qcom_edac driver. Below
> diff allows kernel to autoload it:
> 
> diff --git a/drivers/edac/qcom_edac.c b/drivers/edac/qcom_edac.c
> index f7afb5375293..13919d01c22d 100644
> --- a/drivers/edac/qcom_edac.c
> +++ b/drivers/edac/qcom_edac.c
> @@ -419,3 +419,4 @@ module_platform_driver(qcom_llcc_edac_driver);
>  
>  MODULE_DESCRIPTION("QCOM EDAC driver");
>  MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:qcom_llcc_edac");
> 
> Please test and let me know. I will add this as a new patch in next version.
> 

Thanks Mani, that gets things working for me. For that patch:

Reviewed-by: Andrew Halaney <ahalaney@xxxxxxxxxx>
Tested-by: Andrew Halaney <ahalaney@xxxxxxxxxx>

My personal opinion, but that probably deserves a Fixes: tag too!