From:   "Khandelwal, Rajat" <rajat.khandelwal@intel.com>
To:     "mika.westerberg@linux.intel.com" <mika.westerberg@linux.intel.com>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "platform-driver-x86@vger.kernel.org" 
        <platform-driver-x86@vger.kernel.org>,
        "Westerberg, Mika" <mika.westerberg@intel.com>
Subject: RE: [PATCH] platform/x86: intel_scu_ipc: Keep polling IPC status if
 it reads IPC_STATUS_ERR
Thread-Topic: [PATCH] platform/x86: intel_scu_ipc: Keep polling IPC status if
 it reads IPC_STATUS_ERR
Thread-Index: AQHX/VdVI9fbyn2ZKUGZmpjZsx6tm6xKtDaA
Date:   Thu, 30 Dec 2021 08:30:39 +0000
Message-ID: <CO1PR11MB48359C6EC7DAC17F7FDD91D896459@CO1PR11MB4835.namprd11.prod.outlook.com>
References: <20211230082353.2585-1-rajat.khandelwal@intel.com>
In-Reply-To: <20211230082353.2585-1-rajat.khandelwal@intel.com>
Accept-Language: en-US
Content-Language: en-US
dlp-version: 11.6.200.16
dlp-product: dlpe-windows
dlp-reaction: no-action
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?IjLtMu2MyfGZ960D+xNi6QCjyxBJCl5ssNrMNdm/28351aTdGv+hU+LgeRRa?=
 =?us-ascii?Q?GXlkCz1+GogahvtzRqLyFV56S9odUrxWaI4JMfAA3Zfd4qSqrJz8JBTAqvy6?=
 =?us-ascii?Q?Gw3U2CK6u9MrcDf7AwK08rws2810K2A1voirFnI8rsI4w7tPONmRLUZzNgxP?=
 =?us-ascii?Q?ollc8tBYL4ACzabpDELyxL1xJe+VcHWYQdPUAo2hIFZSMTbkVfJbo1k8LyVr?=
 =?us-ascii?Q?vWiyfc7ZNOFtwEYA66dJNIGe70EeNMhGdcEZ1FYETjkrHx8WJKjRV1bkcJvM?=
 =?us-ascii?Q?7o/DrNJ8zupVEoJKlrgm6opAffjazCvTo+p5Gr9kRDBeO3EcYkuHyuTLGRHX?=
 =?us-ascii?Q?QzitApWrNhxQL+vwfDgSmtHZXJmdutM+4BRjs9DtpxuL2YmQuM6avmjKYW3S?=
 =?us-ascii?Q?h/4f+6Itl/ZZViTI7qo/uE1tkO1YLEoSHwvEQ10ROHjDvKHPEBjztSnmcNch?=
 =?us-ascii?Q?q7YTl5BKQXTI726WfzNtkGmzh355wiq8Z3FD1ifAoDd4MCrODcR/ibdIaqpL?=
 =?us-ascii?Q?K7o8jE4IkJMwPZmVz6WI38QYCT/RCq7aFphSDX95SM/L/7fELFzGiFvKGkeJ?=
 =?us-ascii?Q?tp+RWA1l0bkT4quDag5pBLfoJWsVfpJsll1o6KTZBG1i0EVuQwORX+Yj2GYB?=
 =?us-ascii?Q?6MjprMOmcY5xv/Dmp81gSkdcqXy5xHqeoLyC8wcAbJP2qPgJpZtAiq+o0cEo?=
 =?us-ascii?Q?uL9qYC/SMSmOtK/dwDwNx4/z0pWSzUL5kzBmVVIPIMv085/0fb20eeN0r33V?=
 =?us-ascii?Q?dSoGXdvnc/1zJgOTzGKbA+K7eoGZUzr/DWOxLqntmYeFLQp6AhUgM2goj8uv?=
 =?us-ascii?Q?S6fh471HxD/cdbahDJE2CpxdAJAH9rCxv/OHksIakydXgtKIaV5kKcj5jczO?=
 =?us-ascii?Q?jgA8tBlX7TVSY9qs/s/mhYovHi8suDb5E76hjh+ofoLboMelguVrdgREGVhp?=
 =?us-ascii?Q?U83ny0wOjXZGQdmgji8LgwoEr6tjvbkW3iN5cK+NsjzlTRz7p06gBI9DNgRT?=
 =?us-ascii?Q?wrnOBHt7G7KcUWmOnGDd2PJnvWAIW03AsWCGtXHddbK5FQO5IXAevYIr2dT3?=
 =?us-ascii?Q?rf7jmaL5oASbheU/sF13B2n40qKxqpt2KLbNmwe42nK+JJnTNRuJf9+P5/Wa?=
 =?us-ascii?Q?BU30j88GOPh+kt0rVXi9YNmg+anrxzPehdTOAn+VOdiKH5aud0Es5oJ+Rhdt?=
 =?us-ascii?Q?xr3kbx19+UUVNr1VlHQsaz09l5ejxnKaQsc+1cAfCDBErH/+bo46IpCV4ysn?=
 =?us-ascii?Q?bDqQMNxNtxWYC3CoRkUAhSZ5/9ai++3TgdRgNf+Picam/pwMeIQaA+Uf0fOz?=
 =?us-ascii?Q?X5WkoMDcHYaryzRA01xeoVcuNdp3YoSlhvh3GavMvnE9x/dnh5X/vwfTyxWS?=
 =?us-ascii?Q?yvMbjfs71tbEq4QL3iBSg0t2LDQaFS23kaCjqEyAFaC8d7W6QUcPUmUyyVJd?=
 =?us-ascii?Q?YDAaBwtpNdwVGlx1xanTcuIAstcz5yJgrlnKPdjB9emCpg0z6HzqLdsRBpOC?=
 =?us-ascii?Q?jTVd4cIvwN+jQod8Llf8CblrDLhpwb0bR8YmvLuttotpQ/IJbOR/6z4Bvoj1?=
 =?us-ascii?Q?mVFKSh0rnVCPb5KuPDnDqfnbl+1aD+HyFnHn5dmwo4uppDtxvsFQfenbpkOl?=
 =?us-ascii?Q?Ex5vYfuWLwl/DiZgODDd5L72VVBcxzollUVyDtOgJKyzol7qYjBBBFVy91g/?=
 =?us-ascii?Q?rdA4xQ=3D=3D?=
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: CO1PR11MB4835.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: c3144ab4-fd7d-42f7-5e1e-08d9cb6ea971
X-MS-Exchange-CrossTenant-originalarrivaltime: 30 Dec 2021 08:30:39.7850
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: AeEufjXmq0IW4ggwKOAJky2yWnzxWWngSx7w03X9oGQ6Pa3e8mZvT//wwnnzIu+LJXj0194dxG/SLImdN9J/qSfIjVBNIeL1ff04aPZUhvM=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW4PR11MB5821
X-OriginatorOrg: intel.com
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Hi Mika
I hope this annotation is correct? Sorry for the multiple errors!=20

-----Original Message-----
From: Khandelwal, Rajat <rajat.khandelwal@intel.com>=20
Sent: Thursday, December 30, 2021 1:54 PM
To: mika.westerberg@linux.intel.com
Cc: linux-kernel@vger.kernel.org; platform-driver-x86@vger.kernel.org; Khan=
delwal, Rajat <rajat.khandelwal@intel.com>; Westerberg, Mika <mika.westerbe=
rg@intel.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 retur=
ned and returns -ETIMEDOUT even if the status is busy.
This patch polls the IPC status even if IPC_STATUS_ERR is returned until ti=
meout 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@intel.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/in=
tel_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_de=
v *scu)  {
 	unsigned long end =3D jiffies + IPC_TIMEOUT;
+	u32 status;
=20
 	do {
-		u32 status;
-
 		status =3D 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;
+		}
=20
 		usleep_range(50, 100);
 	} while (time_before(jiffies, end));
=20
+	if (status & IPC_STATUS_BUSY)
+		return -EBUSY;
+	if (status & IPC_STATUS_ERR)
+		return -EIO;
+
 	return -ETIMEDOUT;
 }
=20
--
2.17.1