Hello Mike,
On 2/28/2012 6:26 AM, Mike Frysinger wrote:
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() ?
I'll make the changes and post the patch after testing successfully.
Thanks Amit Virdi