From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756700AbcIHDOk (ORCPT ); Wed, 7 Sep 2016 23:14:40 -0400 Received: from mirror2.csie.ntu.edu.tw ([140.112.30.76]:53240 "EHLO wens.csie.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751934AbcIHDOa (ORCPT ); Wed, 7 Sep 2016 23:14:30 -0400 From: Chen-Yu Tsai To: Kishon Vijay Abraham I , Maxime Ripard Cc: Chen-Yu Tsai , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Hans de Goede , stable@vger.kernel.org Subject: [PATCH] phy: sun4i-usb: Use spinlock to guard phyctl register access Date: Thu, 8 Sep 2016 11:14:18 +0800 Message-Id: <20160908031418.12627-1-wens@csie.org> X-Mailer: git-send-email 2.9.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The musb driver calls into this phy driver to disable/enable squelch detection. This function was introduced in 24fe86a617c5 ("phy: sun4i-usb: Add a sunxi specific function for setting squelch-detect"). This function in turn calls sun4i_usb_phy_write, which uses a mutex to guard the common access register. Unfortunately musb does this in atomic context, which results in the following warning with lock debugging enabled: BUG: sleeping function called from invalid context at kernel/locking/mutex.c:97 in_atomic(): 1, irqs_disabled(): 128, pid: 96, name: kworker/0:2 CPU: 0 PID: 96 Comm: kworker/0:2 Not tainted 4.8.0-rc4-00181-gd502f8ad1c3e #13 Hardware name: Allwinner sun8i Family Workqueue: events musb_deassert_reset [] (unwind_backtrace) from [] (show_stack+0xb/0xc) [] (show_stack) from [] (dump_stack+0x67/0x74) [] (dump_stack) from [] (mutex_lock+0x15/0x2c) [] (mutex_lock) from [] (sun4i_usb_phy_write+0x39/0xec) [] (sun4i_usb_phy_write) from [] (musb_port_reset+0xfb/0x184) [] (musb_port_reset) from [] (musb_deassert_reset+0x1f/0x2c) [] (musb_deassert_reset) from [] (process_one_work+0x129/0x2b8) [] (process_one_work) from [] (worker_thread+0xf3/0x424) [] (worker_thread) from [] (kthread+0xa1/0xb8) [] (kthread) from [] (ret_from_fork+0x11/0x20) Since the register access is mmio, we can use a spinlock to guard this specific access, rather than the mutex that guards the entire phy. Fixes: ba4bdc9e1dc0 ("PHY: sunxi: Add driver for sunxi usb phy") Cc: Hans de Goede Cc: stable@vger.kernel.org Signed-off-by: Chen-Yu Tsai --- drivers/phy/phy-sun4i-usb.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/phy/phy-sun4i-usb.c b/drivers/phy/phy-sun4i-usb.c index fcf4d95ecc6d..ae4ac5457c64 100644 --- a/drivers/phy/phy-sun4i-usb.c +++ b/drivers/phy/phy-sun4i-usb.c @@ -40,6 +40,7 @@ #include #include #include +#include #include #include @@ -115,6 +116,7 @@ struct sun4i_usb_phy_data { const struct sun4i_usb_phy_cfg *cfg; enum usb_dr_mode dr_mode; struct mutex mutex; + spinlock_t reg_lock; /* guard access to phyctl reg */ struct sun4i_usb_phy { struct phy *phy; void __iomem *pmu; @@ -183,7 +185,7 @@ static void sun4i_usb_phy_write(struct sun4i_usb_phy *phy, u32 addr, u32 data, void __iomem *phyctl = phy_data->base + phy_data->cfg->phyctl_offset; int i; - mutex_lock(&phy_data->mutex); + spin_lock(&phy_data->reg_lock); if (phy_data->cfg->type == sun8i_a33_phy || phy_data->cfg->type == sun50i_a64_phy) { @@ -221,7 +223,8 @@ static void sun4i_usb_phy_write(struct sun4i_usb_phy *phy, u32 addr, u32 data, data >>= 1; } - mutex_unlock(&phy_data->mutex); + + spin_unlock(&phy_data->reg_lock); } static void sun4i_usb_phy_passby(struct sun4i_usb_phy *phy, int enable) @@ -583,6 +586,7 @@ static int sun4i_usb_phy_probe(struct platform_device *pdev) return -ENOMEM; mutex_init(&data->mutex); + spin_lock_init(&data->reg_lock); INIT_DELAYED_WORK(&data->detect, sun4i_usb_phy0_id_vbus_det_scan); dev_set_drvdata(dev, data); data->cfg = of_device_get_match_data(dev); -- 2.9.3