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(unknown [109.120.22.104]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20260226090534epsmtip28b0dbcdb88554aca27ecfe58ae41d11f~XwJc0AvJ41180111801epsmtip2M; Thu, 26 Feb 2026 09:05:33 +0000 (GMT) From: "ping.gao" To: shawn.lin@rock-chips.com, ulf.hansson@linaro.org, jh80.chung@samsung.com, krzk+dt@kernel.org, conor+dt@kernel.org, robh@kernel.org Cc: linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, hy50.seo@samsung.com, kwangwon.min@samsung.com, ping.gao@samsung.com Subject: [PATCH v3 2/3] mmc: dw_mmc: Using devm_clk_get_optional() for biu_clk Date: Thu, 26 Feb 2026 17:10:27 +0800 Message-ID: <20260226091027.300564-1-ping.gao@samsung.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CMS-MailID: 20260226090534epcas5p1c5c3ac9afda2d0feb99faa312528f7dc X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P X-CMS-RootMailID: 20260123085150epcas5p42f2cc04843ae7657380b2968261246cb References: 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 --- 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