[U-Boot] [PATCH] USB:host: Attribute packed removed from usb structures

[Mike Frysinger]

On Monday 27 February 2012 15:53:29 Marek Vasut wrote:
> > On Monday 27 February 2012 08:14:26 Marek Vasut wrote:
> > > > On 2/25/2012 3:42 PM, Albert ARIBAUD wrote:
> > > > > Le 24/02/2012 12:58, Amit Virdi a écrit :
> > > > >> Packed attribute is forcing a bytewise write on device registers,
> > > > >> there by, resulting in a misbehavior on gcc-4.4.1.
> > > > >> Reverting the structures to non-packed
> > > > > 
> > > > > If (just asking, not asserting) the issue is caused by fields being
> > > > > u8 where u8 access is not possible, then should you not make the
> > > > > fields u16 / u32 according to access requirements?
> > > > 
> > > > The problem is not with the fields being of a different width. AFAIK,
> > > > the packed attribute changes the generated code to access even the
> > > > word field elements in a byte by byte manner
> > > > 
> > > > Infact, there is a discussion on lkml that I can point
> > > > https://lkml.org/lkml/2011/4/27/278
> > > > 
> > > > It seems that the discussion did not lead to a conclusion but it was
> > > > sensible (at least for ARM) to remove the packed attribute from this
> > > > structure
> > > 
> > > What does the USB spec say ? It might be a HW bug?
> > 
> > it isn't covered by the USB spec.  these are structs for hardware
> > registers in the EHCI usb host controller.
> 
> I see ... so replacing them with unions of accessors where it colides might
> work ?

i'm not entirely sure what you're asking, but i think you're pointing to the 
right answer: drivers/usb/host/ehci.h:ehci_{read,write}l() should *not* be 
casting/derferencing the pointers directly.  they should instead be using 
standard {read,write}l() funcs from asm/io.h.

Amit: can you post a new patch that does that instead ?  don't touch the 
packed attribute, but change ehci_readl() to use readl() and ehci_writel() to 
use writel() ?
-mike
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 836 bytes
Desc: This is a digitally signed message part.
URL: <http://lists.denx.de/pipermail/u-boot/attachments/20120227/79bb511a/attachment.pgp>