2021-12-29 16:14:08

by Rajat Khandelwal

Subject: RE: [PATCH] Keep polling IPC status if it reads IPC_STATUS_BUSY or IPC_STATUS_ERR until timeout expires

Hi @Westerberg, Mika
This was the original message!

-----Original Message-----
From: Khandelwal, Rajat <[email protected]>
Sent: Wednesday, December 29, 2021 7:00 PM
To: [email protected]
Cc: Khandelwal, Rajat <[email protected]>; [email protected]; [email protected]
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 <[email protected]>
---
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

2021-12-29 16:20:00

by Mika Westerberg

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 <[email protected]>
> Sent: Wednesday, December 29, 2021 7:00 PM
> To: [email protected]
> Cc: Khandelwal, Rajat <[email protected]>; [email protected]; [email protected]
> 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 <[email protected]>
> ---
> 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