From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sender4-pp-f112.zoho.com (sender4-pp-f112.zoho.com [136.143.188.112]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 186F241C63; Sun, 4 Jan 2026 06:01:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.188.112 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767506506; cv=pass; b=UahLzkGq90hwt7SAeiB3MbUMZmHFudqbl8TT1JkZVvKy06J/32Zi9YQ0/8tJmHHRie2obFw4A6gM62cgW84lG+7Yp87XdZnZBl2OSsEY+VM4iuSVolC7WEM3WRHMMGwZ6XiasR44Ar4qrd1bNFkb6JLTsKHdDv+3WXjLc0v1mMw= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767506506; c=relaxed/simple; bh=URHLHWBFkdAUYpQKDQWDpVl3NdTUFrIVR1FSydvHaaE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=t6jQ471krcI/rxs9f2GTi1pLyRi3doAE3fI7KCpuhW3J7NERAS6GPJ5hvnTykC1wxciCgjDst5+45egGoIArjJGGrCNT0xzeOHrXwBtjVShosh8kAuY3gOC84naMngPnDqmATj6Y4phnpPvFpuPjfHvRiDli8WEywwqn6sGnAWI= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (1024-bit key) header.d=collabora.com header.i=sebastian.reichel@collabora.com header.b=Z3WxcA0P; arc=pass smtp.client-ip=136.143.188.112 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=collabora.com header.i=sebastian.reichel@collabora.com header.b="Z3WxcA0P" ARC-Seal: i=1; a=rsa-sha256; t=1767506492; cv=none; d=zohomail.com; s=zohoarc; b=P2IOELIq3O0zOgMCr14QqhpYFt0xH5Yh3XvuT0XpD8oPQWY0SygTMT1TWBRKtFyH4pyzyVHqECfD6qkb/sLeJ7cH/5Jtg5Ahk75XQLmqAeS2XNEW2FJv2i8x8/iNOsjTob192Yar7PKFhC9ZvPhny7/YrjT2O2DMr1lA0ac7Y2k= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1767506492; h=Content-Type:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=4Af/BJXu6IcVE7QFcvgpVB6QU2FAMBF4dB3yDzKUElA=; b=FwhknFPmrEuPvEsr2ewVIJRaBu8nPpWxqTNNEAe9hgpmuhisBEAwKqqAXFhZxYrr2o34TKgY2e4gJ7gLmMNOJXtaiE/SivR6e7T4P8A+hlGHF3BLOWOVYNtXAh2ATaxh8diEFtFxYPFoCHkmspmnWNlf/Eo6m0Iu+sOCI9HbwEM= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=sebastian.reichel@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1767506492; s=zohomail; d=collabora.com; i=sebastian.reichel@collabora.com; h=Date:Date:From:From:To:To:Cc:Cc:Subject:Subject:Message-ID:References:MIME-Version:Content-Type:In-Reply-To:Message-Id:Reply-To; bh=4Af/BJXu6IcVE7QFcvgpVB6QU2FAMBF4dB3yDzKUElA=; b=Z3WxcA0Po6tCVH+Nss0fId3ZKMakKWs8pzmXCDZv/F3LGYIFQIg9EW94zpmcz+aV RE6HNzgw+BXCd1j/6qUP4IA1PUedGQbvZjyYwvyKxP/JUs8id0AjoT7lqKuhXdQ22mF XLJ2h0uGRu26AqdyPvkP3x/BPcIuUEZP5bseZH7s= Received: by mx.zohomail.com with SMTPS id 1767506488824204.47840428667007; Sat, 3 Jan 2026 22:01:28 -0800 (PST) Received: by venus (Postfix, from userid 1000) id 3A8DC18086E; Sun, 04 Jan 2026 07:01:26 +0100 (CET) Date: Sun, 4 Jan 2026 07:01:26 +0100 From: Sebastian Reichel To: Shawn Lin Cc: "ping.gao" , jh80.chung@samsung.com, ulf.hansson@linaro.org, linux-kernel@vger.kernel.org, linux-mmc@vger.kernel.org Subject: Re: [PATCH] MMC:dw_mmc:when enable biu_clk should check whether this clk is normal Message-ID: References: <20260104023857.213329-1-ping.gao@samsung.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="j2ranqqlns5n2kha" Content-Disposition: inline In-Reply-To: X-Zoho-Virus-Status: 1 X-Zoho-Virus-Status: 1 X-Zoho-AV-Stamp: zmail-av-1.4.3/267.489.64 X-ZohoMailClient: External --j2ranqqlns5n2kha Content-Type: text/plain; protected-headers=v1; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH] MMC:dw_mmc:when enable biu_clk should check whether this clk is normal MIME-Version: 1.0 Hi, On Sun, Jan 04, 2026 at 10:55:48AM +0800, Shawn Lin wrote: > =E5=9C=A8 2026/01/04 =E6=98=9F=E6=9C=9F=E6=97=A5 10:38, ping.gao =E5=86= =99=E9=81=93: > > some vendor doesn't use biu_clk , enable it will panic > > log is below: >=20 > I still don't understand the real issue you tried to solve. >=20 > host->biu_clk is got via devm_clk_get() in dw_mci_probe(). If > succeed, immediately it's enabled a few lines below. Otherwise, > dw_mci_probe() returns with failure. Seems you are not enabling it in > runtime callbacks, but why clk_prepare_enable(host->biu_clk) is able > to work when driver probed? Based on the error and this patch, I believe what happens is: 1. dw_mci_probe() calls devm_clk_get(host->dev, "biu") 2. The clock does not exist on the platform from Ping Gao, so host->biu_clk gets an error pointer assigned 3. "biu clock not available" gets printed at debug level 4. the error is ignored, but the error pointer is still assigned to host->biu_clk 5. in the runtime PM handler clk_prepare_enable is called for host->biu_clk and thus for an error pointer Instead of hacking this up even further (as this patch does), the proper fix is to cleanup the probe function. I believe the complete biu clock handling in it could be reduced to this: host->biu_clk =3D devm_clk_get_optional_enabled(host->dev, "biu"); ret =3D PTR_ERR_OR_ZERO(host->biu_clk); if (ret) return dev_err_probe(host->dev, ret, "failed to get biu clock\n"); That will assign NULL to host->biu_clk when there is no clock defined and it is fine to run clk_prepare_enable() with NULL as clock pointer. Note, that this will handle the clock enabling as part of devm, so you will also have to drop the clk_disable_unprepare() calls from the err_clk_biu goto label and the extra call from dw_mci_remove(). Something similar should probably be done for host->ciu_clk, which seems to have the same incorrect logic. Greetings, -- Sebastian > > [ 438.400868] [7: binder:436_2: 4998] Unable to handle kernel paging= request at virtual address fffffffffffffffe > > [ 438.400877] [7: binder:436_2: 4998] Mem abort info: > > [ 438.400881] [7: binder:436_2: 4998] ESR =3D 0x0000000096000005 > > [ 438.400887] [7: binder:436_2: 4998] EC =3D 0x25: DABT (current E= L), IL =3D 32 bits > > [ 438.400894] [7: binder:436_2: 4998] SET =3D 0, FnV =3D 0 > > [ 438.400899] [7: binder:436_2: 4998] EA =3D 0, S1PTW =3D 0 > > [ 438.400904] [7: binder:436_2: 4998] FSC =3D 0x05: level 1 transl= ation fault > > ... > > [ 438.409424] [7: binder:436_2: 4998] Call trace: > > [ 438.409429] [7: binder:436_2: 4998] clk_prepare+0x10/0x24 > > [ 438.409439] [7: binder:436_2: 4998] dw_mci_runtime_resume+0x50/0x= 2d8 [dw_mmc_samsung cd210e210975263404c28fc89778f369f8398f0c] > > [ 438.409471] [7: binder:436_2: 4998] dw_mci_exynos_runtime_resume+= 0x18/0x58 [dw_mmc_exynos_samsung 2735a594c7c9c9e8c65b0b87523fbf70dcaabfff] > > [ 438.409496] [7: binder:436_2: 4998] pm_generic_runtime_resume+0x4= 0/0x58 > > [ 438.409506] [7: binder:436_2: 4998] pm_runtime_force_resume+0x9c/= 0x134 > > [ 438.409517] [7: binder:436_2: 4998] platform_pm_resume+0x40/0x8c > > [ 438.409529] [7: binder:436_2: 4998] dpm_run_callback+0x64/0x230 > > [ 438.409540] [7: binder:436_2: 4998] __device_resume+0x1d8/0x394 > > [ 438.409551] [7: binder:436_2: 4998] dpm_resume+0x110/0x2b8 > > [ 438.409561] [7: binder:436_2: 4998] dpm_resume_end+0x1c/0x38 > > [ 438.409570] [7: binder:436_2: 4998] suspend_devices_and_enter+0x8= 28/0xab0 > > [ 438.409582] [7: binder:436_2: 4998] pm_suspend+0x334/0x618 > > [ 438.409592] [7: binder:436_2: 4998] state_store+0x104/0x144 > > [ 438.409601] [7: binder:436_2: 4998] kobj_attr_store+0x30/0x48 > > [ 438.409610] [7: binder:436_2: 4998] sysfs_kf_write+0x54/0x6c > > [ 438.409619] [7: binder:436_2: 4998] kernfs_fop_write_iter+0x104/0= x1a8 > > [ 438.409628] [7: binder:436_2: 4998] vfs_write+0x24c/0x2f4 > > [ 438.409640] [7: binder:436_2: 4998] ksys_write+0x78/0xe8 > > [ 438.409652] [7: binder:436_2: 4998] __arm64_sys_write+0x1c/0x2c > > [ 438.409664] [7: binder:436_2: 4998] invoke_syscall+0x58/0x114 > > [ 438.409676] [7: binder:436_2: 4998] el0_svc_common+0xac/0xe0 > > [ 438.409687] [7: binder:436_2: 4998] do_el0_svc+0x1c/0x28 > > [ 438.409698] [7: binder:436_2: 4998] el0_svc+0x38/0x68 > > [ 438.409705] [7: binder:436_2: 4998] el0t_64_sync_handler+0x68/0xbc > > [ 438.409712] [7: binder:436_2: 4998] el0t_64_sync+0x1a8/0x1ac > > Signed-off-by: ping.gao > > --- > > drivers/mmc/host/dw_mmc.c | 12 +++++++++--- > > 1 file changed, 9 insertions(+), 3 deletions(-) > >=20 > > diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c > > index c5db92bbb094..61f6986f15ef 100644 > > --- a/drivers/mmc/host/dw_mmc.c > > +++ b/drivers/mmc/host/dw_mmc.c > > @@ -3633,9 +3633,15 @@ int dw_mci_runtime_resume(struct device *dev) > > if (host->slot && > > (mmc_host_can_gpio_cd(host->slot->mmc) || > > !mmc_card_is_removable(host->slot->mmc))) { > > - ret =3D clk_prepare_enable(host->biu_clk); > > - if (ret) > > - return ret; > > + if (IS_ERR(host->biu_clk)) { > > + dev_dbg(host->dev, "biu clock not available\n"); > > + } else { > > + ret =3D clk_prepare_enable(host->biu_clk); > > + if (ret) { > > + dev_err(host->dev, "failed to enable biu clock\n"); > > + goto err; > > + } > > + } > > } > > ret =3D clk_prepare_enable(host->ciu_clk); >=20 >=20 --j2ranqqlns5n2kha Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEE72YNB0Y/i3JqeVQT2O7X88g7+poFAmlaAjIACgkQ2O7X88g7 +pqEMRAAhIoXTjfQlyNPVrjfg26ntDx5ffhpYWFLHYnL7RuH3wK4CF9jASlFXjt6 T+nVdesZik6mN/Qcc2m24DLVQ/8Rp60kFJOPwLG8eqsZ8tHkwD7O90hAgjBi4BWh DS8veH/i50hf0mTZ0cgCMVEzweGpvtU3Z/x1+Bb2hH9zi6TarKXZy9GHcokoY/3L WShXsKvW5LbpNk6uX1JjgcXPhcwB5ntP4BzvncXemSbnbS4s6dfY055PpIqZICVa fTXZXD1gTbdmqHoc8rUKF0YOYkvwAjiXn4FYaoWXeFRr+eOaF66EIFHicXItMQCX cvpF/GMGw78Tm1gA0N6dvxFOY/GdI6Qq8UYFqnPXfHd40KjQAISEtBXr0ReEWItf qhTPSwDgE5IyACvzVtw2ezqpZdZyL/kFi78fHDmBlCWq3uRy7elNbGwvFF1qlCDF eO0TkzJXXfSCpjATa4lpyoxWTvMy5pu2MziPK1t8yOj1mwybL5sgW+8Y+cXfBjee jixp8nXQbU6R50UIlu92+eWIvXsTe0Jpvpk79QjagtPCz3YbvGt/CshGPsIawZ+W w6AA/TrD7rbLHrIr2bRORI2TzGLkBfp2B5qDqvhed8opKs2pIe+/9rKkGjiNsrZ7 DkO8aTyVSt0gqRh8AXGo5o6gx6UbIb7n0Md8fwfFwPxqkmG54BE= =vl49 -----END PGP SIGNATURE----- --j2ranqqlns5n2kha--