Messages in this thread | | | Subject | Re: [PATCH v2] phy: sun4i-usb: Use spinlock to guard phyctl register access | From | Hans de Goede <> | Date | Fri, 9 Sep 2016 11:43:22 +0200 |
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Hi,
On 09-09-16 05:58, Chen-Yu Tsai wrote: > 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 > [<c010bc01>] (unwind_backtrace) from [<c0109237>] (show_stack+0xb/0xc) > [<c0109237>] (show_stack) from [<c02a669b>] (dump_stack+0x67/0x74) > [<c02a669b>] (dump_stack) from [<c05d68c9>] (mutex_lock+0x15/0x2c) > [<c05d68c9>] (mutex_lock) from [<c02c3589>] (sun4i_usb_phy_write+0x39/0xec) > [<c02c3589>] (sun4i_usb_phy_write) from [<c03e6327>] (musb_port_reset+0xfb/0x184) > [<c03e6327>] (musb_port_reset) from [<c03e4917>] (musb_deassert_reset+0x1f/0x2c) > [<c03e4917>] (musb_deassert_reset) from [<c012ecb5>] (process_one_work+0x129/0x2b8) > [<c012ecb5>] (process_one_work) from [<c012f5e3>] (worker_thread+0xf3/0x424) > [<c012f5e3>] (worker_thread) from [<c0132dbd>] (kthread+0xa1/0xb8) > [<c0132dbd>] (kthread) from [<c0105f31>] (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 <hdegoede@redhat.com> > Cc: stable@vger.kernel.org > Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Looks good to me:
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Regards,
Hans
> --- > > Changes since v1: > > - Remove the old mutex, since it is no longer used > - Use irqsave/irqrestore variant of spinlock ops > > --- > drivers/phy/phy-sun4i-usb.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/drivers/phy/phy-sun4i-usb.c b/drivers/phy/phy-sun4i-usb.c > index fcf4d95ecc6d..34b7f0c2e019 100644 > --- a/drivers/phy/phy-sun4i-usb.c > +++ b/drivers/phy/phy-sun4i-usb.c > @@ -40,6 +40,7 @@ > #include <linux/power_supply.h> > #include <linux/regulator/consumer.h> > #include <linux/reset.h> > +#include <linux/spinlock.h> > #include <linux/usb/of.h> > #include <linux/workqueue.h> > > @@ -114,7 +115,7 @@ struct sun4i_usb_phy_data { > void __iomem *base; > 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; > @@ -181,9 +182,10 @@ static void sun4i_usb_phy_write(struct sun4i_usb_phy *phy, u32 addr, u32 data, > struct sun4i_usb_phy_data *phy_data = to_sun4i_usb_phy_data(phy); > u32 temp, usbc_bit = BIT(phy->index * 2); > void __iomem *phyctl = phy_data->base + phy_data->cfg->phyctl_offset; > + unsigned long flags; > int i; > > - mutex_lock(&phy_data->mutex); > + spin_lock_irqsave(&phy_data->reg_lock, flags); > > 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_irqrestore(&phy_data->reg_lock, flags); > } > > static void sun4i_usb_phy_passby(struct sun4i_usb_phy *phy, int enable) > @@ -582,7 +585,7 @@ static int sun4i_usb_phy_probe(struct platform_device *pdev) > if (!data) > 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); >
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