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From: Marek Vasut <marex@denx.de>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH] usb: remove unnecessary packed attributes
Date: Thu, 30 Aug 2012 22:59:53 +0200	[thread overview]
Message-ID: <201208302259.53564.marex@denx.de> (raw)
In-Reply-To: <201208301749.11276.marex@denx.de>

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 ge?ndert, 2 Zeilen hinzugef?gt(+), 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

  reply	other threads:[~2012-08-30 20:59 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-08-30 15:41 [U-Boot] [PATCH] usb: remove unnecessary packed attributes Lucas Stach
2012-08-30 15:49 ` Marek Vasut
2012-08-30 20:59   ` Marek Vasut [this message]
2012-08-30 21:42     ` Lucas Stach
2012-08-30 21:56       ` Marek Vasut

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