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[PATCH 1/3] tty: nozomi: avoid a harmless gcc warning

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  [PATCH 1/3] tty: nozomi: avoid a harmless gcc warning Arnd Bergmann <arnd@arndb.de> - 2016-01-25 23:00 +0100
    [PATCH 3/3] tty: hvc_xen: hide xen_console_remove when unused Arnd Bergmann <arnd@arndb.de> - 2016-01-25 23:00 +0100
      Re: [PATCH 3/3] tty: hvc_xen: hide xen_console_remove when unused Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-01-26 00:10 +0100
        Re: [PATCH 3/3] tty: hvc_xen: hide xen_console_remove when unused Stefano Stabellini <stefano.stabellini@eu.citrix.com> - 2016-01-26 13:30 +0100
    [PATCH 2/3] tty: cyclades: cyz_interrupt is only used for PCI Arnd Bergmann <arnd@arndb.de> - 2016-01-25 23:00 +0100

#1317332 — [PATCH 1/3] tty: nozomi: avoid a harmless gcc warning

The nozomi wireless data driver has its own helper function to
transfer data from a FIFO, doing an extra byte swap on big-endian
architectures, presumably to bring the data back into byte-serial
order after readw() or readl() perform their implicit byteswap.

This helper function is used in the receive_data() function to
first read the length into a 32-bit variable, which causes
a compile-time warning:

drivers/tty/nozomi.c: In function 'receive_data':
drivers/tty/nozomi.c:857:9: warning: 'size' may be used uninitialized in this function [-Wmaybe-uninitialized]

The problem is that gcc is unsure whether the data was actually
read or not. We know that it is at this point, so we can replace
it with a single readl() to shut up that warning.

I am leaving the byteswap in there, to preserve the existing
behavior, even though this seems fishy: Reading the length of
the data into a cpu-endian variable should normally not use
a second byteswap on big-endian systems, unless the hardware
is aware of the CPU endianess.

There appears to be a lot more confusion about endianess in this
driver, so it probably has not worked on big-endian systems in
a long time, if ever, and I have no way to test it. It's well
possible that this driver has not been used by anyone in a while,
the last patch that looks like it was tested on the hardware is
from 2008.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/tty/nozomi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/nozomi.c b/drivers/tty/nozomi.c
index 80f9de907563..5cc80b80c82b 100644
--- a/drivers/tty/nozomi.c
+++ b/drivers/tty/nozomi.c
@@ -823,7 +823,7 @@ static int receive_data(enum port_type index, struct nozomi *dc)
 	struct tty_struct *tty = tty_port_tty_get(&port->port);
 	int i, ret;
 
-	read_mem32((u32 *) &size, addr, 4);
+	size = __le32_to_cpu(readl(addr));
 	/*  DBG1( "%d bytes port: %d", size, index); */
 
 	if (tty && test_bit(TTY_THROTTLED, &tty->flags)) {
-- 
2.7.0

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#1317333 — [PATCH 3/3] tty: hvc_xen: hide xen_console_remove when unused

xencons_disconnect_backend() is only called from xen_console_remove(),
which is conditionally compiled, so we get a harmless warning when
CONFIG_HVC_XEN_FRONTEND is unset:

hvc/hvc_xen.c:350:12: error: 'xen_console_remove' defined but not used [-Werror=unused-function]

This moves the function down into the same #ifdef section to silence
the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/tty/hvc/hvc_xen.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index fa816b7193b6..11725422dacb 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -323,6 +323,7 @@ void xen_console_resume(void)
 	}
 }
 
+#ifdef CONFIG_HVC_XEN_FRONTEND
 static void xencons_disconnect_backend(struct xencons_info *info)
 {
 	if (info->irq > 0)
@@ -363,7 +364,6 @@ static int xen_console_remove(struct xencons_info *info)
 	return 0;
 }
 
-#ifdef CONFIG_HVC_XEN_FRONTEND
 static int xencons_remove(struct xenbus_device *dev)
 {
 	return xen_console_remove(dev_get_drvdata(&dev->dev));
-- 
2.7.0

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#1317395 — Re: [PATCH 3/3] tty: hvc_xen: hide xen_console_remove when unused

On 01/25/2016 04:54 PM, Arnd Bergmann wrote:
> xencons_disconnect_backend() is only called from xen_console_remove(),

and also from xencons_probe()/xencons_resume(). But those two are also 
under the
same ifdef.

-boris

> which is conditionally compiled, so we get a harmless warning when
> CONFIG_HVC_XEN_FRONTEND is unset:
>
> hvc/hvc_xen.c:350:12: error: 'xen_console_remove' defined but not used [-Werror=unused-function]
>
> This moves the function down into the same #ifdef section to silence
> the warning.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>   drivers/tty/hvc/hvc_xen.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
> index fa816b7193b6..11725422dacb 100644
> --- a/drivers/tty/hvc/hvc_xen.c
> +++ b/drivers/tty/hvc/hvc_xen.c
> @@ -323,6 +323,7 @@ void xen_console_resume(void)
>   	}
>   }
>   
> +#ifdef CONFIG_HVC_XEN_FRONTEND
>   static void xencons_disconnect_backend(struct xencons_info *info)
>   {
>   	if (info->irq > 0)
> @@ -363,7 +364,6 @@ static int xen_console_remove(struct xencons_info *info)
>   	return 0;
>   }
>   
> -#ifdef CONFIG_HVC_XEN_FRONTEND
>   static int xencons_remove(struct xenbus_device *dev)
>   {
>   	return xen_console_remove(dev_get_drvdata(&dev->dev));

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#1317832 — Re: [PATCH 3/3] tty: hvc_xen: hide xen_console_remove when unused

On Mon, 25 Jan 2016, Boris Ostrovsky wrote:
> On 01/25/2016 04:54 PM, Arnd Bergmann wrote:
> > xencons_disconnect_backend() is only called from xen_console_remove(),
> 
> and also from xencons_probe()/xencons_resume(). But those two are also under
> the
> same ifdef.

Good point. Aside from this the patch is good.

 
> > which is conditionally compiled, so we get a harmless warning when
> > CONFIG_HVC_XEN_FRONTEND is unset:
> > 
> > hvc/hvc_xen.c:350:12: error: 'xen_console_remove' defined but not used
> > [-Werror=unused-function]
> > 
> > This moves the function down into the same #ifdef section to silence
> > the warning.
> > 
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> >   drivers/tty/hvc/hvc_xen.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
> > index fa816b7193b6..11725422dacb 100644
> > --- a/drivers/tty/hvc/hvc_xen.c
> > +++ b/drivers/tty/hvc/hvc_xen.c
> > @@ -323,6 +323,7 @@ void xen_console_resume(void)
> >   	}
> >   }
> >   +#ifdef CONFIG_HVC_XEN_FRONTEND
> >   static void xencons_disconnect_backend(struct xencons_info *info)
> >   {
> >   	if (info->irq > 0)
> > @@ -363,7 +364,6 @@ static int xen_console_remove(struct xencons_info *info)
> >   	return 0;
> >   }
> >   -#ifdef CONFIG_HVC_XEN_FRONTEND
> >   static int xencons_remove(struct xenbus_device *dev)
> >   {
> >   	return xen_console_remove(dev_get_drvdata(&dev->dev));
> 

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#1317336 — [PATCH 2/3] tty: cyclades: cyz_interrupt is only used for PCI

When CONFIG_PCI is not set, enabling CONFIG_CYZ_INTR has no
practical effect other than generating a warning about an
unused function:

drivers/tty/cyclades.c:1184:20: warning: 'cyz_interrupt' defined but not used [-Wunused-function]
 static irqreturn_t cyz_interrupt(int irq, void *dev_id)

This adds a dependency to avoid that warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/tty/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
index c01f45095877..82c4d2e45319 100644
--- a/drivers/tty/Kconfig
+++ b/drivers/tty/Kconfig
@@ -226,7 +226,7 @@ config CYCLADES
 
 config CYZ_INTR
 	bool "Cyclades-Z interrupt mode operation"
-	depends on CYCLADES
+	depends on CYCLADES && PCI
 	help
 	  The Cyclades-Z family of multiport cards allows 2 (two) driver op
 	  modes: polling and interrupt. In polling mode, the driver will check
-- 
2.7.0

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