linux-kernel - Re: [PATCH v4 10/12] remoteproc: mediatek: Handle MT8195 SCP core 1 watchdog timeout

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Date:   Thu, 9 Feb 2023 13:48:55 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Tinghan Shen <tinghan.shen@...iatek.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v4 10/12] remoteproc: mediatek: Handle MT8195 SCP core 1
 watchdog timeout

Il 09/02/23 08:40, Tinghan Shen ha scritto:
> The MT8195 SCP core 1 watchdog timeout needs to be handled in the
> SCP core 0 IRQ handler because the MT8195 SCP core 1 watchdog timeout
> IRQ is wired on the same IRQ entry for core 0 watchdog timeout.
> MT8195 SCP has a watchdog status register to identify the watchdog
> timeout source when IRQ triggered.
> 
> Signed-off-by: Tinghan Shen <tinghan.shen@...iatek.com>
> ---
>   drivers/remoteproc/mtk_common.h |  4 ++++
>   drivers/remoteproc/mtk_scp.c    | 24 +++++++++++++++++++++++-
>   2 files changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/remoteproc/mtk_common.h b/drivers/remoteproc/mtk_common.h
> index e4ef97f2d3a1..ca2395b98d27 100644
> --- a/drivers/remoteproc/mtk_common.h
> +++ b/drivers/remoteproc/mtk_common.h
> @@ -55,6 +55,10 @@
>   #define MT8192_CORE0_WDT_IRQ		0x10030
>   #define MT8192_CORE0_WDT_CFG		0x10034
>   
> +#define MT8195_SYS_STATUS		0x4004
> +#define MT8195_CORE0_WDT		BIT(16)
> +#define MT8195_CORE1_WDT		BIT(17)
> +
>   #define MT8195_L1TCM_SRAM_PDN_RESERVED_RSI_BITS		GENMASK(7, 4)
>   
>   #define MT8195_CPU1_SRAM_PD			0x1084
> diff --git a/drivers/remoteproc/mtk_scp.c b/drivers/remoteproc/mtk_scp.c
> index cfcb719ba50b..9fbbc4751433 100644
> --- a/drivers/remoteproc/mtk_scp.c
> +++ b/drivers/remoteproc/mtk_scp.c
> @@ -222,6 +222,28 @@ static void mt8192_scp_irq_handler(struct mtk_scp *scp)
>   	}
>   }
>   
> +static void mt8195_scp_irq_handler(struct mtk_scp *scp)

Looking at the C1 interrupt handler, I don't see any WDT timeout handling, hence
a question naturally arises:

Would it ever be possible for *both* CORE0 and CORE1 WDT timeout to happen
at the same time?

Meaning that MT8195_SYS_STATUS has *both* CORE0_WDT and CORE1_WDT bits set when
we reach this interrupt handler?
In that case, the fix would be to just change....

> +{
> +	u32 scp_to_host;
> +
> +	scp_to_host = readl(scp->reg_base + MT8192_SCP2APMCU_IPC_SET);
> +
> +	if (scp_to_host & MT8192_SCP_IPC_INT_BIT) {
> +		scp_ipi_handler(scp);
> +	} else {
> +		u32 reason = readl(scp->reg_base + MT8195_SYS_STATUS);
> +
> +		if (reason & MT8195_CORE1_WDT)
> +			writel(1, scp->reg_base + MT8195_CORE1_WDT_IRQ);
> +		else

...the 'else' to another conditional :-)

Regards,
Angelo