linux-kernel - Re: [RESEND PATCH v2] soc: mediatek: PMIC wrap: Clear the vldclr if state machine stay on FSM

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Date:	Fri, 8 Jan 2016 10:43:52 +0800
From:	Ricky Liang <jcliang@...omium.org>
To:	Henry Chen <henryc.chen@...iatek.com>
Cc:	Matthias Brugger <matthias.bgg@...il.com>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	"moderated list:ARM/Mediatek SoC..." 
	<linux-arm-kernel@...ts.infradead.org>,
	"moderated list:ARM/Mediatek SoC..." 
	<linux-mediatek@...ts.infradead.org>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH v2] soc: mediatek: PMIC wrap: Clear the vldclr if
 state machine stay on FSM_VLDCLR state.

On Mon, Jan 4, 2016 at 8:02 PM, Henry Chen <henryc.chen@...iatek.com> wrote:
>
> Sometimes PMIC is too busy to send data in time to cause pmic wrap timeout,
> because pmic wrap is waiting for FSM_VLDCLR after finishing WACS2_CMD. It
> just return error when issue happened, so the state machine will stay on
> FSM_VLDCLR state when data send back later by PMIC and timeout again in next
> time because pmic wrap waiting for FSM_IDLE state at the beginning of the
> read/write function.
>
> Clear the vldclr when timeout if state machine stay on FSM_VLDCLR.
>
> Signed-off-by: Henry Chen <henryc.chen@...iatek.com>
> ---
> Changes since v1:
> Encapsulated the code in a inline function, and add a descriptive comment.
> ---
>  drivers/soc/mediatek/mtk-pmic-wrap.c | 30 ++++++++++++++++++++++++++++--
>  1 file changed, 28 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/soc/mediatek/mtk-pmic-wrap.c b/drivers/soc/mediatek/mtk-pmic-wrap.c
> index 105597a..af919b1 100644
> --- a/drivers/soc/mediatek/mtk-pmic-wrap.c
> +++ b/drivers/soc/mediatek/mtk-pmic-wrap.c
> @@ -412,6 +412,12 @@ static bool pwrap_is_fsm_vldclr(struct pmic_wrapper *wrp)
>         return PWRAP_GET_WACS_FSM(val) == PWRAP_WACS_FSM_WFVLDCLR;
>  }
>
> +static inline void pwrap_leave_fsm_vldclr(struct pmic_wrapper *wrp)
> +{
> +       if (pwrap_is_fsm_vldclr(wrp))
> +               pwrap_writel(wrp, 1, PWRAP_WACS2_VLDCLR);
> +}
> +
>  static bool pwrap_is_sync_idle(struct pmic_wrapper *wrp)
>  {
>         return pwrap_readl(wrp, PWRAP_WACS2_RDATA) & PWRAP_STATE_SYNC_IDLE0;
> @@ -445,8 +451,18 @@ static int pwrap_write(struct pmic_wrapper *wrp, u32 adr, u32 wdata)
>         int ret;
>
>         ret = pwrap_wait_for_state(wrp, pwrap_is_fsm_idle);
> -       if (ret)
> +       if (ret) {
> +               /*
> +                * Timeout issue sometimes caused by the last read command
> +                * failed because pmic wrap could not got the FSM_VLDCLR
> +                * in time after finishing WACS2_CMD. It made state machine
> +                * still on FSM_VLDCLR and timeout next time.
> +                * Check the status of FSM and clear the vldclr to recovery the
> +                * error.
> +                */
> +               pwrap_leave_fsm_vldclr(wrp);
>                 return ret;
> +       }
>
>         pwrap_writel(wrp, (1 << 31) | ((adr >> 1) << 16) | wdata,
>                         PWRAP_WACS2_CMD);
> @@ -459,8 +475,18 @@ static int pwrap_read(struct pmic_wrapper *wrp, u32 adr, u32 *rdata)
>         int ret;
>
>         ret = pwrap_wait_for_state(wrp, pwrap_is_fsm_idle);
> -       if (ret)
> +       if (ret) {
> +               /*
> +                * Timeout issue sometimes caused by the last read command
> +                * failed because pmic wrap could not got the FSM_VLDCLR
> +                * in time after finishing WACS2_CMD. It made state machine
> +                * still on FSM_VLDCLR and timeout next time.
> +                * Check the status of FSM and clear the vldclr to recovery the
> +                * error.
> +                */
> +               pwrap_leave_fsm_vldclr(wrp);
>                 return ret;
> +       }
>
>         pwrap_writel(wrp, (adr >> 1) << 16, PWRAP_WACS2_CMD);
>
> --
> 1.9.1
>
> --
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Tested-by: Ricky Liang <jcliang@...omium.org>

On our test platform this patch fixes PMIC communication erros.