linux-kernel - Re: [PATCH] Keep polling IPC status if it reads IPC_STATUS_BUSY or IPC_STATUS

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Message-ID: <YcyKoZyBFzRtwRMm@lahna>
Date:   Wed, 29 Dec 2021 18:19:45 +0200
From:   "mika.westerberg@...ux.intel.com" <mika.westerberg@...ux.intel.com>
To:     "Khandelwal, Rajat" <rajat.khandelwal@...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>
Subject: Re: [PATCH] Keep polling IPC status if it reads IPC_STATUS_BUSY or
 IPC_STATUS_ERR until timeout expires

Hi,

Now I got it.

Please run checkpatch.pl and fix all the issues it reports, and change
the $subject line to match the style in that file and then re-send.
Thanks!

On Wed, Dec 29, 2021 at 06:13:56PM +0200, Khandelwal, Rajat wrote:
> Hi @Westerberg, Mika
> This was the original message!
> 
> -----Original Message-----
> From: Khandelwal, Rajat <rajat.khandelwal@...el.com>
> Sent: Wednesday, December 29, 2021 7:00 PM
> To: mika.westerberg@...ux.intel.com
> Cc: Khandelwal, Rajat <rajat.khandelwal@...el.com>; linux-kernel@...r.kernel.org; platform-driver-x86@...r.kernel.org
> Subject: [PATCH] Keep polling IPC status if it reads IPC_STATUS_BUSY or IPC_STATUS_ERR until timeout expires
> 
> 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 | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/platform/x86/intel_scu_ipc.c b/drivers/platform/x86/intel_scu_ipc.c
> index 7cc9089d1e14..91f716e84474 100644
> --- a/drivers/platform/x86/intel_scu_ipc.c
> +++ b/drivers/platform/x86/intel_scu_ipc.c
> @@ -233,17 +233,19 @@ 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_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