Patchwork [U-Boot] usb: remove unnecessary packed attributes

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Submitter Lucas Stach
Date Aug. 30, 2012, 3:41 p.m.
Message ID <1346341281-12923-1-git-send-email-dev@lynxeye.de>
Download mbox | patch
Permalink /patch/180828/
State Not Applicable
Delegated to: Marek Vasut
Headers show

Comments

Lucas Stach - Aug. 30, 2012, 3:41 p.m.
We don't actually need to pack those structs, as they
are not used to do actual hardware access.

This avoids some unaligned accesses and therefore makes
the EHCI stack work on ARMv7 without compiler workarounds.

Signed-off-by: Lucas Stach <dev@lynxeye.de>
---
 drivers/usb/host/ehci-hcd.c | 2 +-
 include/usb.h               | 2 +-
 2 Dateien geändert, 2 Zeilen hinzugefügt(+), 2 Zeilen entfernt(-)
Marek Vasut - Aug. 30, 2012, 3:49 p.m.
Dear Lucas Stach,

> We don't actually need to pack those structs, as they
> are not used to do actual hardware access.
> 
> This avoids some unaligned accesses and therefore makes
> the EHCI stack work on ARMv7 without compiler workarounds.
> 
> Signed-off-by: Lucas Stach <dev@lynxeye.de>

I need to review this properly, will get back to it soon.

Until then, CCing other good fellows.

> ---
>  drivers/usb/host/ehci-hcd.c | 2 +-
>  include/usb.h               | 2 +-
>  2 Dateien geändert, 2 Zeilen hinzugefügt(+), 2 Zeilen entfernt(-)
> 
> diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
> index 18b4bc6..2f4fa5e 100644
> --- a/drivers/usb/host/ehci-hcd.c
> +++ b/drivers/usb/host/ehci-hcd.c
> @@ -45,7 +45,7 @@ static struct descriptor {
>  	struct usb_linux_config_descriptor config;
>  	struct usb_linux_interface_descriptor interface;
>  	struct usb_endpoint_descriptor endpoint;
> -}  __attribute__ ((packed)) descriptor = {
> +} descriptor = {
>  	{
>  		0x8,		/* bDescLength */
>  		0x29,		/* bDescriptorType: hub descriptor */
> diff --git a/include/usb.h b/include/usb.h
> index ba3d169..63730ee 100644
> --- a/include/usb.h
> +++ b/include/usb.h
> @@ -369,7 +369,7 @@ struct usb_hub_descriptor {
>  	unsigned char  PortPowerCtrlMask[(USB_MAXCHILDREN+1+7)/8];
>  	/* DeviceRemovable and PortPwrCtrlMask want to be variable-length
>  	   bitmaps that hold max 255 entries. (bit0 is ignored) */
> -} __attribute__ ((packed));
> +};
> 
> 
>  struct usb_hub_device {

Best regards,
Marek Vasut
Marek Vasut - Aug. 30, 2012, 8:59 p.m.
Dear Marek Vasut,

> Dear Lucas Stach,
> 
> > We don't actually need to pack those structs, as they
> > are not used to do actual hardware access.
> > 
> > This avoids some unaligned accesses and therefore makes
> > the EHCI stack work on ARMv7 without compiler workarounds.
> > 
> > Signed-off-by: Lucas Stach <dev@lynxeye.de>
> 
> I need to review this properly, will get back to it soon.

My 7th sense is telling me, these descriptors are sent across the bus. 
ehci_submit_root() puts them into buffer and then ehci_submit_async() blasts 
them. I believe they must be packed, otherwise the format expected by devices on 
the bus won't match and it'll fall apart.

> Until then, CCing other good fellows.
> 
> > ---
> > 
> >  drivers/usb/host/ehci-hcd.c | 2 +-
> >  include/usb.h               | 2 +-
> >  2 Dateien geändert, 2 Zeilen hinzugefügt(+), 2 Zeilen entfernt(-)
> > 
> > diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
> > index 18b4bc6..2f4fa5e 100644
> > --- a/drivers/usb/host/ehci-hcd.c
> > +++ b/drivers/usb/host/ehci-hcd.c
> > @@ -45,7 +45,7 @@ static struct descriptor {
> > 
> >  	struct usb_linux_config_descriptor config;
> >  	struct usb_linux_interface_descriptor interface;
> >  	struct usb_endpoint_descriptor endpoint;
> > 
> > -}  __attribute__ ((packed)) descriptor = {
> > +} descriptor = {
> > 
> >  	{
> >  	
> >  		0x8,		/* bDescLength */
> >  		0x29,		/* bDescriptorType: hub descriptor */
> > 
> > diff --git a/include/usb.h b/include/usb.h
> > index ba3d169..63730ee 100644
> > --- a/include/usb.h
> > +++ b/include/usb.h
> > @@ -369,7 +369,7 @@ struct usb_hub_descriptor {
> > 
> >  	unsigned char  PortPowerCtrlMask[(USB_MAXCHILDREN+1+7)/8];
> >  	/* DeviceRemovable and PortPwrCtrlMask want to be variable-length
> >  	
> >  	   bitmaps that hold max 255 entries. (bit0 is ignored) */
> > 
> > -} __attribute__ ((packed));
> > +};
> > 
> >  struct usb_hub_device {
> 
> Best regards,
> Marek Vasut

Best regards,
Marek Vasut
Lucas Stach - Aug. 30, 2012, 9:42 p.m.
Dear Marek,

it seems you are right. Though it works for me this may be pure luck. So
please disregard this patch, I'll fix this up more properly.

Thanks,
Lucas

Am Donnerstag, den 30.08.2012, 22:59 +0200 schrieb Marek Vasut:
> Dear Marek Vasut,
> 
> > Dear Lucas Stach,
> > 
> > > We don't actually need to pack those structs, as they
> > > are not used to do actual hardware access.
> > > 
> > > This avoids some unaligned accesses and therefore makes
> > > the EHCI stack work on ARMv7 without compiler workarounds.
> > > 
> > > Signed-off-by: Lucas Stach <dev@lynxeye.de>
> > 
> > I need to review this properly, will get back to it soon.
> 
> My 7th sense is telling me, these descriptors are sent across the bus. 
> ehci_submit_root() puts them into buffer and then ehci_submit_async() blasts 
> them. I believe they must be packed, otherwise the format expected by devices on 
> the bus won't match and it'll fall apart.
> 
> > Until then, CCing other good fellows.
> > 
> > > ---
> > > 
> > >  drivers/usb/host/ehci-hcd.c | 2 +-
> > >  include/usb.h               | 2 +-
> > >  2 Dateien geändert, 2 Zeilen hinzugefügt(+), 2 Zeilen entfernt(-)
> > > 
> > > diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
> > > index 18b4bc6..2f4fa5e 100644
> > > --- a/drivers/usb/host/ehci-hcd.c
> > > +++ b/drivers/usb/host/ehci-hcd.c
> > > @@ -45,7 +45,7 @@ static struct descriptor {
> > > 
> > >  	struct usb_linux_config_descriptor config;
> > >  	struct usb_linux_interface_descriptor interface;
> > >  	struct usb_endpoint_descriptor endpoint;
> > > 
> > > -}  __attribute__ ((packed)) descriptor = {
> > > +} descriptor = {
> > > 
> > >  	{
> > >  	
> > >  		0x8,		/* bDescLength */
> > >  		0x29,		/* bDescriptorType: hub descriptor */
> > > 
> > > diff --git a/include/usb.h b/include/usb.h
> > > index ba3d169..63730ee 100644
> > > --- a/include/usb.h
> > > +++ b/include/usb.h
> > > @@ -369,7 +369,7 @@ struct usb_hub_descriptor {
> > > 
> > >  	unsigned char  PortPowerCtrlMask[(USB_MAXCHILDREN+1+7)/8];
> > >  	/* DeviceRemovable and PortPwrCtrlMask want to be variable-length
> > >  	
> > >  	   bitmaps that hold max 255 entries. (bit0 is ignored) */
> > > 
> > > -} __attribute__ ((packed));
> > > +};
> > > 
> > >  struct usb_hub_device {
> > 
> > Best regards,
> > Marek Vasut
> 
> Best regards,
> Marek Vasut
>
Marek Vasut - Aug. 30, 2012, 9:56 p.m.
Dear Lucas Stach,

> Dear Marek,
> 
> it seems you are right. Though it works for me this may be pure luck. So
> please disregard this patch, I'll fix this up more properly.

Cool thing we caught it :-)

http://www.denx.de/wiki/U-Boot/Patches btw read up here ... don't top-post ... 
you know the drill.

> Thanks,
> Lucas
> 
> Am Donnerstag, den 30.08.2012, 22:59 +0200 schrieb Marek Vasut:
> > Dear Marek Vasut,
> > 
> > > Dear Lucas Stach,
> > > 
> > > > We don't actually need to pack those structs, as they
> > > > are not used to do actual hardware access.
> > > > 
> > > > This avoids some unaligned accesses and therefore makes
> > > > the EHCI stack work on ARMv7 without compiler workarounds.
> > > > 
> > > > Signed-off-by: Lucas Stach <dev@lynxeye.de>
> > > 
> > > I need to review this properly, will get back to it soon.
> > 
> > My 7th sense is telling me, these descriptors are sent across the bus.
> > ehci_submit_root() puts them into buffer and then ehci_submit_async()
> > blasts them. I believe they must be packed, otherwise the format
> > expected by devices on the bus won't match and it'll fall apart.
> > 
> > > Until then, CCing other good fellows.
> > > 
> > > > ---
> > > > 
> > > >  drivers/usb/host/ehci-hcd.c | 2 +-
> > > >  include/usb.h               | 2 +-
> > > >  2 Dateien geändert, 2 Zeilen hinzugefügt(+), 2 Zeilen entfernt(-)
> > > > 
> > > > diff --git a/drivers/usb/host/ehci-hcd.c
> > > > b/drivers/usb/host/ehci-hcd.c index 18b4bc6..2f4fa5e 100644
> > > > --- a/drivers/usb/host/ehci-hcd.c
> > > > +++ b/drivers/usb/host/ehci-hcd.c
> > > > @@ -45,7 +45,7 @@ static struct descriptor {
> > > > 
> > > >  	struct usb_linux_config_descriptor config;
> > > >  	struct usb_linux_interface_descriptor interface;
> > > >  	struct usb_endpoint_descriptor endpoint;
> > > > 
> > > > -}  __attribute__ ((packed)) descriptor = {
> > > > +} descriptor = {
> > > > 
> > > >  	{
> > > >  	
> > > >  		0x8,		/* bDescLength */
> > > >  		0x29,		/* bDescriptorType: hub descriptor */
> > > > 
> > > > diff --git a/include/usb.h b/include/usb.h
> > > > index ba3d169..63730ee 100644
> > > > --- a/include/usb.h
> > > > +++ b/include/usb.h
> > > > @@ -369,7 +369,7 @@ struct usb_hub_descriptor {
> > > > 
> > > >  	unsigned char  PortPowerCtrlMask[(USB_MAXCHILDREN+1+7)/8];
> > > >  	/* DeviceRemovable and PortPwrCtrlMask want to be variable-
length
> > > >  	
> > > >  	   bitmaps that hold max 255 entries. (bit0 is ignored) */
> > > > 
> > > > -} __attribute__ ((packed));
> > > > +};
> > > > 
> > > >  struct usb_hub_device {
> > > 
> > > Best regards,
> > > Marek Vasut
> > 
> > Best regards,
> > Marek Vasut

Best regards,
Marek Vasut

Patch

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 18b4bc6..2f4fa5e 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -45,7 +45,7 @@  static struct descriptor {
 	struct usb_linux_config_descriptor config;
 	struct usb_linux_interface_descriptor interface;
 	struct usb_endpoint_descriptor endpoint;
-}  __attribute__ ((packed)) descriptor = {
+} descriptor = {
 	{
 		0x8,		/* bDescLength */
 		0x29,		/* bDescriptorType: hub descriptor */
diff --git a/include/usb.h b/include/usb.h
index ba3d169..63730ee 100644
--- a/include/usb.h
+++ b/include/usb.h
@@ -369,7 +369,7 @@  struct usb_hub_descriptor {
 	unsigned char  PortPowerCtrlMask[(USB_MAXCHILDREN+1+7)/8];
 	/* DeviceRemovable and PortPwrCtrlMask want to be variable-length
 	   bitmaps that hold max 255 entries. (bit0 is ignored) */
-} __attribute__ ((packed));
+};
 
 
 struct usb_hub_device {