From:   Meng Li <Meng.Li@windriver.com>
To:     thor.thayer@linux.intel.com, lee.jones@linaro.org, arnd@arndb.de
Cc:     linux-kernel@vger.kernel.org, meng.li@windriver.com
Subject: [PATCH] mfd: altera-sysmgr: enable raw spinlock feature for preempt-rt kernel
Date:   Tue, 16 Nov 2021 18:54:24 +0800
Message-Id: <20211116105424.12685-1-Meng.Li@windriver.com>
Content-Type: text/plain
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?nH0Dz1QO8s8RyMn9fevzcYUlzMuop2xMhppJE4MWXIHt5aV8x7P9ilbIoRtd?=
 =?us-ascii?Q?YX9yqZuTIOKyJyHTCmrNpiZOzt2uSiBS2U420g3b/bgptwVlQI4SDm71wAc5?=
 =?us-ascii?Q?2I/l+izoqv33DqM/gomRVd5sSQW3z79inKyipqBJ2OTXebq2tlVlGB4u8wGG?=
 =?us-ascii?Q?tVy/FHIgVG2VZUHfaQlGY5EpePO+tkF3zCm6/TjZcRy1cEy6PmKoTH3cPUel?=
 =?us-ascii?Q?3eL4fm1/DZPToGCMULV2uk12d6ENWhisROZcMYL7P25pb1NbjE3T0rpNI860?=
 =?us-ascii?Q?1sh9OUb0KADOTixOGN2NECmru14EEdezFw/YWjWxtd6GQGTVApgZfGTBoPaH?=
 =?us-ascii?Q?3tS1/2+11oM2MkYJRCinOIAbB44qL4K+bqWCxQfGDBzn/k9rekfeKDWi3DMX?=
 =?us-ascii?Q?tl6mE5nO7NDjYUehZdXbwBAU4yqtC6rFdkY5jyUMtHL7tpqatUkF9ToYncQ0?=
 =?us-ascii?Q?Wstpr+j+a8VgR5gnEmX5erOLbv7jGg/oj8Tjh2fG1KuAecedtWR8+I7aiifL?=
 =?us-ascii?Q?n7SzZKbfWk3q5FJLVz1fUHHgAdlsMeTnfwz4zLTYlrBU+XYM2SXeKvGr5/39?=
 =?us-ascii?Q?xD13n7mWykP2bWZjGA0bQBjuaiQQaN3iHIHstLok3XpSAMl5NMqJdgsk68We?=
 =?us-ascii?Q?/951DXR1ST7lc7fQiNFfGColnDhmPCnZx3TNTkdK2EAJasoqDyy8Vr3Xlcz0?=
 =?us-ascii?Q?M6VmUnQiRVBOfXGkm/VI1a0hATjQDRcK0KVMF+MGHxlwbdnz5o52sPhR2QDQ?=
 =?us-ascii?Q?1rJbcGIBdMmjvmlA4W0eL2PWNsuOtqpx3OJUJ8XZ5lvLbhx31wAyam5Ik+xW?=
 =?us-ascii?Q?vLiYPcKYLCYJisqSn1abSAyMpUXbVjvf28cCoDsrhd9LsMSbvFZTfWSDRAM+?=
 =?us-ascii?Q?KtjGIqtr8obuQPtmNgzPoQUlgO5WBJukehUoO4nLdjdNS4n24AO7/A8uqY0X?=
 =?us-ascii?Q?YzA6LxqLEmCWS/gKqZToiyj24mYsOEAb5UdAUsHmzI94PWVi6HmVO6xyDW5k?=
 =?us-ascii?Q?Xrjtc4AWUgU28+OVMoNiQ3duN5UPhayymdf9YkAzgf7l/B/3BAJTh/lb2UJL?=
 =?us-ascii?Q?58zMZV0jDNw7o/e6tDJy87GPGB+HWXjQ7cxlSObHNiEn6e/RtZ+PLI8unl4q?=
 =?us-ascii?Q?P+bVGo/iZrWrBndYLk0QM8S/j8k68pCSkfK80GHMAtnki3nhcbLijkMMkbVV?=
 =?us-ascii?Q?lwRJXPqSCZ+NlHDhjImS+UYc1i8ZoyHTGD3sGS1ga1T4TpekYFrnz/4PzEXA?=
 =?us-ascii?Q?L8iDrKw5cyXtCQnNATCc2BgjMnjHZHsO4FGuwSmfRHngQRoo1iok2yLtWnKb?=
 =?us-ascii?Q?VlyKWzlZzHsgvxTRhUmlLKul3tdIhvYp1qtZta2TA/wgVtSvbesSONfu7Fhw?=
 =?us-ascii?Q?RUeapCt0U9QG9WYMd79m9iNh9u+LUUAOHCc34smuAFQ8k5xzSV/dR8ocujO2?=
 =?us-ascii?Q?N8kLxIRzX7yr4wMTT0s7onL8kEkx2Kp7AFlKTymX42dlaCxNj4iBGBq2FVzL?=
 =?us-ascii?Q?U7ofOKqX+nfNHFGBgE1bH1ADCmXflxfrMVfzg4RP975BzPgoNncCqgxWXVWA?=
 =?us-ascii?Q?R0C3fxQWkjWAb979MwL27u8q/axbHzzpKhIQl5nSc4WY9GpxvwPniW2ybj91?=
 =?us-ascii?Q?yvKTk0INQprVfQdn3KLpI5Y=3D?=
X-OriginatorOrg: windriver.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 7ebc702b-9db4-4038-b78d-08d9a8ef995f
X-MS-Exchange-CrossTenant-AuthSource: PH0PR11MB5191.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Nov 2021 10:55:27.6200
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 8ddb2873-a1ad-4a18-ae4e-4644631433be
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: m0m5HhZCSYN2MHSMi2RiPgIrfgzljH5o4Xeo4f6QbXOOkpEK1nmuGyachM5GU53PWlfIeeyk9kA1IE1y7Oo/lA==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR11MB5861
X-Proofpoint-ORIG-GUID: xj2GbxnCkue6JUslHOHH5jjlWfVLNfnj
X-Proofpoint-GUID: xj2GbxnCkue6JUslHOHH5jjlWfVLNfnj
X-Proofpoint-Virus-Version: vendor=baseguard
 engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.0.607.475
 definitions=2021-11-16_01,2021-11-16_01,2020-04-07_01
X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 impostorscore=0
 mlxlogscore=999 suspectscore=0 mlxscore=0 bulkscore=0 spamscore=0
 priorityscore=1501 adultscore=0 malwarescore=0 phishscore=0
 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1
 engine=8.12.0-2110150000 definitions=main-2111160055
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

When booting up preempt rt kernel on stratix10 platform, there is
below calltrace:
BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:969
in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 1, name: swapper/0
Preemption disabled at:
[<ffff8000100b25b0>] __setup_irq+0xe0/0x730
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.10.78-rt54-yocto-preempt-rt #1
Hardware name: SoCFPGA Stratix 10 SoCDK (DT)
Call trace:
 ......
 ___might_sleep+0x144/0x180
 rt_spin_lock+0x34/0x9c
 regmap_lock_spinlock+0x24/0x40
 regmap_write+0x48/0x84
 a10_eccmgr_irq_unmask+0x34/0x40
 ......
 altr_edac_a10_probe+0x16c/0x2b0
 platform_drv_probe+0x60/0xb4
 ......
 ret_from_fork+0x10/0x38

Because regmap_write is invoked under preemption disabled status, and
might trigger sleep.
Recently, the commit 67021f25d952("regmap: teach regmap to use raw
spinlocks if requested in the config ") add an option for regmap to use
raw spinlock. So, enable raw spinlock in preempt-rt kernel to avoid the
might sleep issue.
Note: The commit 67021f25d952 is only in kernel v5.15, not included in
earlier versions. So, if intend to fix this issue in earlier preempt-rt
kernel, it is need to backport the 2 patches together, otherwise there
will be building issue.

Signed-off-by: Meng Li <Meng.Li@windriver.com>
---

v2:
 - improve the patch title.
 - improve the commit log. Clear which commit is depended by this patch.

---
 drivers/mfd/altera-sysmgr.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/mfd/altera-sysmgr.c b/drivers/mfd/altera-sysmgr.c
index 5d3715a28b28..27271cec5d53 100644
--- a/drivers/mfd/altera-sysmgr.c
+++ b/drivers/mfd/altera-sysmgr.c
@@ -83,6 +83,9 @@ static struct regmap_config altr_sysmgr_regmap_cfg = {
 	.fast_io = true,
 	.use_single_read = true,
 	.use_single_write = true,
+#ifdef CONFIG_PREEMPT_RT
+	.use_raw_spinlock = true,
+#endif
 };
 
 /**
-- 
2.17.1