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

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Date:   Fri, 31 May 2019 16:05:28 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Neil Armstrong <narmstrong@...libre.com>
CC:     <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-amlogic@...ts.infradead.org>
Subject: Re: [PATCH] phy: meson-g12a-usb3-pcie: disable locking for cr_regmap

Hi,

On 31/05/19 4:01 PM, Neil Armstrong wrote:
> Fix the following BUG by disabling locking for the cr_regmap config.

What caused the BUG in the first place? The commit log needs more details or
else this looks like a workaround to mask a BUG.

Thanks
Kishon

> 
> 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>
> ---
>  drivers/phy/amlogic/phy-meson-g12a-usb3-pcie.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/phy/amlogic/phy-meson-g12a-usb3-pcie.c b/drivers/phy/amlogic/phy-meson-g12a-usb3-pcie.c
> index 6233a7979a93..ac322d643c7a 100644
> --- a/drivers/phy/amlogic/phy-meson-g12a-usb3-pcie.c
> +++ b/drivers/phy/amlogic/phy-meson-g12a-usb3-pcie.c
> @@ -188,7 +188,7 @@ static const struct regmap_config phy_g12a_usb3_pcie_cr_regmap_conf = {
>  	.reg_read = phy_g12a_usb3_pcie_cr_bus_read,
>  	.reg_write = phy_g12a_usb3_pcie_cr_bus_write,
>  	.max_register = 0xffff,
> -	.fast_io = true,
> +	.disable_locking = true,
>  };
>  
>  static int phy_g12a_usb3_init(struct phy *phy)
>