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Date:   Sun, 26 Jan 2020 21:41:56 +0530
From:   Saurav Girepunje <saurav.girepunje@gmail.com>
To:     b-liu@ti.com, gregkh@linuxfoundation.org,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     saurav.girepunje@hotmail.com
Subject: [PATCH] usb: musb: Fix external abort on non-linefetch
Message-ID: <20200126161156.GA20401@google.com>
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While accessing the usb mode/vbus from sysfs. Below error came on kernel
version 4.19.

On latest kernel vserion api name changed. Therefore API
name and backtrace API names are different.

     [  821.908066] Backtrace:
     [  821.910695] [<bf078fc0>] (musb_default_readl [musb_hdrc]) from [<bf0af738>] (dsps_musb_set_mode+0x38/0x12c [musb_dsps])
     [  821.922059] [<bf0af700>] (dsps_musb_set_mode [musb_dsps]) from [<bf07899c>] (musb_mode_store+0xc8/0x12c [musb_hdrc])
     [  821.933105]  r7:a0010013 r6:0000000b r5:cd79d200 r4:cb634010
     [  821.939096] [<bf0788d4>] (musb_mode_store [musb_hdrc]) from [<c0425184>] (dev_attr_store+0x20/0x2c)
     [  821.948593]  r7:cd79d200 r6:c5abbf78 r5:00000000 r4:bf0788d4
     [  821.954549] [<c0425164>] (dev_attr_store) from [<c0285b08>] (sysfs_kf_write+0x48/0x4c)
     [  821.962859]  r5:00000000 r4:c0425164
     [  821.966620] [<c0285ac0>] (sysfs_kf_write) from [<c0285274>] (kernfs_fop_write+0xfc/0x1fc)
     [  821.975200]  r5:00000000 r4:cd79d080
     [  821.978966] [<c0285178>] (kernfs_fop_write) from [<c020ec00>] (__vfs_write+0x34/0x120)
     [  821.987280]  r10:00000000 r9:0000000b r8:00000000 r7:0000000b r6:c5abbf78 r5:c0285178
     [  821.995493]  r4:cb67a3c0
     [  821.998160] [<c020ebcc>] (__vfs_write) from [<c020fae8>] (vfs_write+0xa8/0x170)
     [  822.005835]  r9:0000000b r8:00000000 r7:c5abbf78 r6:000def80 r5:cb67a3c0 r4:0000000b
     [  822.013969] [<c020fa40>] (vfs_write) from [<c02108d0>] (SyS_write+0x44/0x98)
     [  822.021371]  r9:0000000b r8:000def80 r7:00000000 r6:00000000 r5:cb67a3c0 r4:cb67a3c0
     [  822.029517] [<c021088c>] (SyS_write) from [<c010d8a0>] (ret_fast_syscall+0x0/0x3c)
     [  822.037467]  r9:c5aba000 r8:c010daa8 r7:00000004 r6:b6f0ad58 r5:000def80 r4:0000000b
     [  822.045599] Code: e1a0c00d e92dd800 e24cb004 e0801001 (e5910000)

Without pm_runtime_{get,put}_sync calls in place,
Similar issue come on "mode_show" and "vbus_store" also.

fix- call pm_runtime_{get,put}_sync before reading/writing
usb mode/vbus from sysfs.

Signed-off-by: Saurav Girepunje <saurav.girepunje@gmail.com>
---
  drivers/usb/musb/musb_core.c | 6 ++++++
  1 file changed, 6 insertions(+)

diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
index 5ebf30b..a1ca8380 100644
--- a/drivers/usb/musb/musb_core.c
+++ b/drivers/usb/musb/musb_core.c
@@ -1723,9 +1723,11 @@ int musb_mailbox(enum musb_vbus_id_status status)
  	unsigned long flags;
  	int ret;
  
+	pm_runtime_get_sync(dev);
  	spin_lock_irqsave(&musb->lock, flags);
  	ret = sprintf(buf, "%s\n", usb_otg_state_string(musb->xceiv->otg->state));
  	spin_unlock_irqrestore(&musb->lock, flags);
+	pm_runtime_put_sync(dev);
  
  	return ret;
  }
@@ -1738,6 +1740,7 @@ int musb_mailbox(enum musb_vbus_id_status status)
  	unsigned long	flags;
  	int		status;
  
+	pm_runtime_get_sync(dev);
  	spin_lock_irqsave(&musb->lock, flags);
  	if (sysfs_streq(buf, "host"))
  		status = musb_platform_set_mode(musb, MUSB_HOST);
@@ -1748,6 +1751,7 @@ int musb_mailbox(enum musb_vbus_id_status status)
  	else
  		status = -EINVAL;
  	spin_unlock_irqrestore(&musb->lock, flags);
+	pm_runtime_put_sync(dev);
  
  	return (status == 0) ? n : status;
  }
@@ -1766,6 +1770,7 @@ int musb_mailbox(enum musb_vbus_id_status status)
  		return -EINVAL;
  	}
  
+	pm_runtime_get_sync(dev);
  	spin_lock_irqsave(&musb->lock, flags);
  	/* force T(a_wait_bcon) to be zero/unlimited *OR* valid */
  	musb->a_wait_bcon = val ? max_t(int, val, OTG_TIME_A_WAIT_BCON) : 0 ;
@@ -1773,6 +1778,7 @@ int musb_mailbox(enum musb_vbus_id_status status)
  		musb->is_active = 0;
  	musb_platform_try_idle(musb, jiffies + msecs_to_jiffies(val));
  	spin_unlock_irqrestore(&musb->lock, flags);
+	pm_runtime_put_sync(dev);
  
  	return n;
  }
-- 
1.9.1