Re: [PATCH v2] remoteproc/mediatek: enable MPU for all memory regions in MT8192 SCP

[Mathieu Poirier <mathieu.poirier@linaro.org>]

On Thu, Jan 07, 2021 at 10:30:20AM +0800, Tzung-Bi Shih wrote:
> The register MT8192_CORE0_MEM_ATT_PREDEF contains attributes for each
> memory region.  It defines whether a memory region can be managed by MPU
> or not.
> 
> In the past, due to the default settings in the register, MT8192 SCP
> works luckily.  After enabling L1TCM, SCP starts to access memory region
> that is not included in the default settings.  As a result, SCP hangs.
> 
> Enables MPU for all memory regions in MT8192 SCP.
> 
> Note that the register is read only once when SCP resets.  Thus, it must
> be set from kernel side.

Much better - now I understand what is going on.  

Based on the description of the problem please add a "Fixes" tag and CC stable.
I also suggest you bundle this patch with your other patchset [1] once you have
make the modifications for devm_platform_ioremap_resource_byname().

Thanks,
Mathieu

[1]. https://patchwork.kernel.org/project/linux-remoteproc/list/?series=401287

> 
> Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
> ---
> Changes from v1[1]:
> - Adds more details in commit message.
> 
> [1]: https://patchwork.kernel.org/project/linux-remoteproc/patch/20201214051047.859110-1-tzungbi@google.com/ 
> 
>  drivers/remoteproc/mtk_common.h | 1 +
>  drivers/remoteproc/mtk_scp.c    | 3 +++
>  2 files changed, 4 insertions(+)
> 
> diff --git a/drivers/remoteproc/mtk_common.h b/drivers/remoteproc/mtk_common.h
> index 94bc54b224ee..5f7cd2336cef 100644
> --- a/drivers/remoteproc/mtk_common.h
> +++ b/drivers/remoteproc/mtk_common.h
> @@ -47,6 +47,7 @@
>  
>  #define MT8192_CORE0_SW_RSTN_CLR	0x10000
>  #define MT8192_CORE0_SW_RSTN_SET	0x10004
> +#define MT8192_CORE0_MEM_ATT_PREDEF	0x10008
>  #define MT8192_CORE0_WDT_CFG		0x10034
>  
>  #define SCP_FW_VER_LEN			32
> diff --git a/drivers/remoteproc/mtk_scp.c b/drivers/remoteproc/mtk_scp.c
> index f025aba67abc..130c0b9511df 100644
> --- a/drivers/remoteproc/mtk_scp.c
> +++ b/drivers/remoteproc/mtk_scp.c
> @@ -369,6 +369,9 @@ static int mt8192_scp_before_load(struct mtk_scp *scp)
>  	mt8192_power_on_sram(scp->reg_base + MT8192_L1TCM_SRAM_PDN);
>  	mt8192_power_on_sram(scp->reg_base + MT8192_CPU0_SRAM_PD);
>  
> +	/* enable MPU for all memory regions */
> +	writel(0xff, scp->reg_base + MT8192_CORE0_MEM_ATT_PREDEF);
> +
>  	return 0;
>  }
>  
> -- 
> 2.29.2.729.g45daf8777d-goog
> 

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