From: "ping.gao" <ping.gao@samsung.com>
To: ulf.hansson@linaro.org, jh80.chung@samsung.com
Cc: shawn.lin@rock-chips.com, krzk@kernel.org, krzk+dt@kernel.org,
robh@kernel.org, conor+dt@kernel.org, linux-mmc@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
kwangwon.min@samsung.com, hy50.seo@samsung.com,
Ping Gao <ping.gao@samsung.com>
Subject: [PATCH v4 3/3] mmc: dw_mmc: Using devm_clk_get_optional() for biu_clk
Date: Sat, 28 Feb 2026 14:24:57 +0800 [thread overview]
Message-ID: <20260228062457.3210099-4-ping.gao@samsung.com> (raw)
In-Reply-To: <20260228062457.3210099-1-ping.gao@samsung.com>
From: Ping Gao <ping.gao@samsung.com>
By using devm_clk_get_optional, if clk is optional for device and not define in dts
it will return NULL, then clk_prepare_enable/clk_disable_unprepare for biu_clk is safe to
bail out internally.
before biu_clk in dwmmc driver devm_clk_get fail, but it's ERR_PTR,
not null,it will panic when call clk_prepare
log is below:
[7: binder:436_2: 4998] Unable to handle kernel paging request at virtual address fffffffffffffffe
[7: binder:436_2: 4998] Mem abort info:
[7: binder:436_2: 4998] ESR = 0x0000000096000005
[7: binder:436_2: 4998] EC = 0x25: DABT (current EL), IL = 32 bits
[7: binder:436_2: 4998] SET = 0, FnV = 0
[7: binder:436_2: 4998] EA = 0, S1PTW = 0
[7: binder:436_2: 4998] FSC = 0x05: level 1 translation fault
...
[7: binder:436_2: 4998] Call trace:
[7: binder:436_2: 4998] clk_prepare+0x10/0x24
[7: binder:436_2: 4998] dw_mci_runtime_resume+0x50/0x2d8 [dw_mmc_samsung cd210e210975263404c28fc89778f369f8398f0c]
[7: binder:436_2: 4998] dw_mci_exynos_runtime_resume+0x18/0x58 [dw_mmc_exynos_samsung 2735a594c7c9c9e8c65b0b87523fbf70dcaabfff]
[7: binder:436_2: 4998] pm_generic_runtime_resume+0x40/0x58
[7: binder:436_2: 4998] pm_runtime_force_resume+0x9c/0x134
[7: binder:436_2: 4998] platform_pm_resume+0x40/0x8c
[7: binder:436_2: 4998] dpm_run_callback+0x64/0x230
[7: binder:436_2: 4998] __device_resume+0x1d8/0x394
[7: binder:436_2: 4998] dpm_resume+0x110/0x2b8
[7: binder:436_2: 4998] dpm_resume_end+0x1c/0x38
[7: binder:436_2: 4998] suspend_devices_and_enter+0x828/0xab0
[7: binder:436_2: 4998] pm_suspend+0x334/0x618
[7: binder:436_2: 4998] state_store+0x104/0x144
[7: binder:436_2: 4998] kobj_attr_store+0x30/0x48
[7: binder:436_2: 4998] sysfs_kf_write+0x54/0x6c
[7: binder:436_2: 4998] kernfs_fop_write_iter+0x104/0x1a8
[7: binder:436_2: 4998] vfs_write+0x24c/0x2f4
[7: binder:436_2: 4998] ksys_write+0x78/0xe8
[7: binder:436_2: 4998] __arm64_sys_write+0x1c/0x2c
[7: binder:436_2: 4998] invoke_syscall+0x58/0x114
[7: binder:436_2: 4998] el0_svc_common+0xac/0xe0
[7: binder:436_2: 4998] do_el0_svc+0x1c/0x28
[7: binder:436_2: 4998] el0_svc+0x38/0x68
[7: binder:436_2: 4998] el0t_64_sync_handler+0x68/0xbc
[7: binder:436_2: 4998] el0t_64_sync+0x1a8/0x1ac
Signed-off-by: Ping Gao <ping.gao@samsung.com>
---
drivers/mmc/host/dw_mmc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index c5db92bbb094..6bcc1e7233c0 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -3375,7 +3375,7 @@ int dw_mci_probe(struct dw_mci *host)
"platform data not available\n");
}
- host->biu_clk = devm_clk_get(host->dev, "biu");
+ host->biu_clk = devm_clk_get_optional(host->dev, "biu");
if (IS_ERR(host->biu_clk)) {
dev_dbg(host->dev, "biu clock not available\n");
ret = PTR_ERR(host->biu_clk);
--
2.50.1
next prev parent reply other threads:[~2026-02-28 6:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20260228062020epcas5p1e498c4fc67f590f4243645288c492f01@epcas5p1.samsung.com>
2026-02-28 6:24 ` [PATCH v4 0/3] mmc: dw_mmc: Support optional BIU clock ping.gao
2026-02-28 6:24 ` [PATCH v4 1/3] dt-bindings: mmc: synopsys-dw-mshc: relax clocks constraint ping.gao
2026-02-28 9:44 ` Krzysztof Kozlowski
2026-02-28 10:12 ` Krzysztof Kozlowski
2026-03-06 2:05 ` ping.gao
2026-02-28 6:24 ` [PATCH v4 2/3] mmc: dw_mmc-k3: before set biu_clk rate, check biu_clk available or not ping.gao
2026-02-28 6:24 ` ping.gao [this message]
2026-02-28 9:44 ` [PATCH v4 3/3] mmc: dw_mmc: Using devm_clk_get_optional() for biu_clk Krzysztof Kozlowski
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