linux-kernel - Re: [PATCH] platform/x86: intel_scu_ipc: Keep polling IPC status if it reads IPC_STATUS

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Date:   Sat, 1 Jan 2022 14:03:51 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     "Khandelwal, Rajat" <rajat.khandelwal@...el.com>,
        "mika.westerberg@...ux.intel.com" <mika.westerberg@...ux.intel.com>,
        "Krogerus, Heikki" <heikki.krogerus@...el.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        "Westerberg, Mika" <mika.westerberg@...el.com>
Subject: Re: [PATCH] platform/x86: intel_scu_ipc: Keep polling IPC status if
 it reads IPC_STATUS_ERR

Hi Rajat,

On 12/31/21 16:49, Khandelwal, Rajat wrote:
> Adding ++Heikki
> 
> Thanks
> Rajat

If you want me to apply this, please send this as a proper patch, not as an inline
forward to me, with the platform-driver-x86@...r.kernel.org list in the Cc.

Regards,

Hans


> -----Original Message-----
> From: Khandelwal, Rajat <rajat.khandelwal@...el.com> 
> Sent: Thursday, December 30, 2021 1:54 PM
> To: mika.westerberg@...ux.intel.com
> Cc: linux-kernel@...r.kernel.org; platform-driver-x86@...r.kernel.org; Khandelwal, Rajat <rajat.khandelwal@...el.com>; Westerberg, Mika <mika.westerberg@...el.com>
> Subject: [PATCH] platform/x86: intel_scu_ipc: Keep polling IPC status if it reads IPC_STATUS_ERR
> 
> The current implementation returns -EIO if and when IPC_STATUS_ERR is returned and returns -ETIMEDOUT even if the status is busy.
> This patch polls the IPC status even if IPC_STATUS_ERR is returned until timeout expires and returns -EBUSY if the status shows busy.
> Observed in multiple scenarios, trying to fetch the status of IPC after it shows ERR sometimes eradicates the ERR status.
> 
> Signed-off-by: Rajat-Khandelwal <rajat.khandelwal@...el.com>
> ---
>  drivers/platform/x86/intel_scu_ipc.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/platform/x86/intel_scu_ipc.c b/drivers/platform/x86/intel_scu_ipc.c
> index 7cc9089d1e14..1f90acaa7212 100644
> --- a/drivers/platform/x86/intel_scu_ipc.c
> +++ b/drivers/platform/x86/intel_scu_ipc.c
> @@ -233,17 +233,23 @@ static inline u32 ipc_data_readl(struct intel_scu_ipc_dev *scu, u32 offset)  static inline int busy_loop(struct intel_scu_ipc_dev *scu)  {
>  	unsigned long end = jiffies + IPC_TIMEOUT;
> +	u32 status;
>  
>  	do {
> -		u32 status;
> -
>  		status = ipc_read_status(scu);
> -		if (!(status & IPC_STATUS_BUSY))
> -			return (status & IPC_STATUS_ERR) ? -EIO : 0;
> +		if (!(status & IPC_STATUS_BUSY)) {
> +			if (!(status & IPC_STATUS_ERR))
> +				return 0;
> +		}
>  
>  		usleep_range(50, 100);
>  	} while (time_before(jiffies, end));
>  
> +	if (status & IPC_STATUS_BUSY)
> +		return -EBUSY;
> +	if (status & IPC_STATUS_ERR)
> +		return -EIO;
> +
>  	return -ETIMEDOUT;
>  }
>  
> --
> 2.17.1
>