linux-kernel - Re: [PATCH v2] phy: meson-g12a-usb3-pcie: disable locking for cr

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Date:   Fri, 07 Jun 2019 15:57:11 -0700
From:   Kevin Hilman <khilman@...libre.com>
To:     Neil Armstrong <narmstrong@...libre.com>, kishon@...com
Cc:     Neil Armstrong <narmstrong@...libre.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org
Subject: Re: [PATCH v2] phy: meson-g12a-usb3-pcie: disable locking for cr_regmap

Neil Armstrong <narmstrong@...libre.com> writes:

> Locking is not needed for the phy_g12a_usb3_pcie_cr_bus_read/write() and
> currently it causes the following BUG because of the usage of the
> regmap_read_poll_timeout() running in spinlock_irq, configured by regmap fast_io.
>
> Simply disable locking in the cr_regmap config since it's only used from the
> PHY init callback function.
>
> BUG: sleeping function called from invalid context at drivers/phy/amlogic/phy-meson-g12a-usb3-pcie.c:85
> in_atomic(): 1, irqs_disabled(): 128, pid: 60, name: kworker/3:1
> [snip]
> Workqueue: events deferred_probe_work_func
> Call trace:
>  dump_backtrace+0x0/0x190
>  show_stack+0x14/0x20
>  dump_stack+0x90/0xb4
>  ___might_sleep+0xec/0x110
>  __might_sleep+0x50/0x88
>  phy_g12a_usb3_pcie_cr_bus_addr.isra.0+0x80/0x1a8
>  phy_g12a_usb3_pcie_cr_bus_read+0x34/0x1d8
>  _regmap_read+0x60/0xe0
>  _regmap_update_bits+0xc4/0x110
>  regmap_update_bits_base+0x60/0x90
>  phy_g12a_usb3_pcie_init+0xdc/0x210
>  phy_init+0x74/0xd0
>  dwc3_meson_g12a_probe+0x2cc/0x4d0
>  platform_drv_probe+0x50/0xa0
>  really_probe+0x20c/0x3b8
>  driver_probe_device+0x68/0x150
>  __device_attach_driver+0xa8/0x170
>  bus_for_each_drv+0x64/0xc8
>  __device_attach+0xd8/0x158
>  device_initial_probe+0x10/0x18
>  bus_probe_device+0x90/0x98
>  deferred_probe_work_func+0x94/0xe8
>  process_one_work+0x1e0/0x338
>  worker_thread+0x230/0x458
>  kthread+0x134/0x138
>  ret_from_fork+0x10/0x1c
>
> Fixes: 36077e16c050 ("phy: amlogic: Add Amlogic G12A USB3 + PCIE Combo PHY Driver")
> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>

Tested-by: Kevin Hilman <khilman@...libre.com>