linux-kernel - Re: [PATCH 1/3] usb: pci-quirks: Add a header for SB800 I/O ports and mutex for locking

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Date:   Sat, 1 Apr 2017 15:59:57 +0200
From:   Greg KH <greg@...ah.com>
To:     Zoltan Boszormenyi <zboszor@...hu>
Cc:     linux-usb@...r.kernel.org, linux-watchdog@...r.kernel.org,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] usb: pci-quirks: Add a header for SB800 I/O ports
 and mutex for locking

On Sat, Apr 01, 2017 at 01:02:21PM +0200, Zoltan Boszormenyi wrote:
> From: Böszörményi Zoltán <zboszor@...hu>
> 
> This patch adds:
> * a mutex in the USB PCI quirks code for synchronizing access to
>   the I/O ports on SB800
> * a new header that contains symbols for the index and data I/O ports
>   and wrappers for locking and unlocking the mutex.
> * locking around the I/O port access for SB800
> 
> Signed-off-by: Zoltan Boszormenyi <zboszor@...hu>
> ---
>  drivers/usb/host/pci-quirks.c | 14 ++++++++++----
>  include/linux/sb800.h         | 15 +++++++++++++++
>  2 files changed, 25 insertions(+), 4 deletions(-)
>  create mode 100644 include/linux/sb800.h
> 
> diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c
> index a9a1e4c..9b0445c 100644
> --- a/drivers/usb/host/pci-quirks.c
> +++ b/drivers/usb/host/pci-quirks.c
> @@ -15,6 +15,7 @@
>  #include <linux/export.h>
>  #include <linux/acpi.h>
>  #include <linux/dmi.h>
> +#include <linux/sb800.h>
>  #include "pci-quirks.h"
>  #include "xhci-ext-caps.h"
>  
> @@ -279,6 +280,9 @@ bool usb_amd_prefetch_quirk(void)
>  }
>  EXPORT_SYMBOL_GPL(usb_amd_prefetch_quirk);
>  
> +DEFINE_MUTEX(sb800_mutex);
> +EXPORT_SYMBOL_GPL(sb800_mutex);
> +
>  /*
>   * The hardware normally enables the A-link power management feature, which
>   * lets the system lower the power consumption in idle states.
> @@ -314,11 +318,13 @@ static void usb_amd_quirk_pll(int disable)
>  	if (amd_chipset.sb_type.gen == AMD_CHIPSET_SB800 ||
>  			amd_chipset.sb_type.gen == AMD_CHIPSET_HUDSON2 ||
>  			amd_chipset.sb_type.gen == AMD_CHIPSET_BOLTON) {
> -		outb_p(AB_REG_BAR_LOW, 0xcd6);
> -		addr_low = inb_p(0xcd7);
> -		outb_p(AB_REG_BAR_HIGH, 0xcd6);
> -		addr_high = inb_p(0xcd7);
> +		enter_sb800();
> +		outb_p(AB_REG_BAR_LOW, SB800_PIIX4_SMB_IDX);
> +		addr_low = inb_p(SB800_PIIX4_SMB_DATA);
> +		outb_p(AB_REG_BAR_HIGH, SB800_PIIX4_SMB_IDX);
> +		addr_high = inb_p(SB800_PIIX4_SMB_DATA);
>  		addr = addr_high << 8 | addr_low;
> +		leave_sb800();
>  
>  		outl_p(0x30, AB_INDX(addr));
>  		outl_p(0x40, AB_DATA(addr));
> diff --git a/include/linux/sb800.h b/include/linux/sb800.h
> new file mode 100644
> index 0000000..5650b7d
> --- /dev/null
> +++ b/include/linux/sb800.h
> @@ -0,0 +1,15 @@
> +
> +#ifndef SB800_H
> +#define SB800_H
> +
> +#include <linux/mutex.h>
> +
> +#define SB800_PIIX4_SMB_IDX		0xcd6
> +#define SB800_PIIX4_SMB_DATA	0xcd7
> +
> +extern struct mutex sb800_mutex;
> +
> +#define enter_sb800()	mutex_lock(&sb800_mutex)
> +#define leave_sb800()	mutex_unlock(&sb800_mutex)

Don't hide the mutex, just spell it out in the code itself.  No need for
these defines at all.

thanks,

greg k-h