Sven Luther wrote:
This requires a lot of care to do right. Remember that on PC systems
interrupts can be substantially posted. A "stop_interrupt" may prevent
IRQ issue but if an IRQ is already on the PC APIC bus it will kill you
later on because the IRQ delivery and PCI bus access on the PC class
machines are totally asynchronous
I think this part could be interresting to apply if the Kernel team is
sure that it won't hurt other platform.
And what about the other part of the patch ? The one about the
alignement of the buffer descriptors ? Does it seem sound, should we
ward it with ppc specific stuff ? Is it fit to be included in the main
kernel ?
I don't think the problem is alignement nor cache cohenry.
In fact, I'm pretty sure that cache cohenrency on this platform is reliable.
It's a really weird.
If I modify the structure to :
struct uhci_qh {
/* Hardware fields */
u32 link; /* Next queue */
u32 element; /* Queue element pointer */
/* Software fields */
dma_addr_t dma_handle;
struct usb_device *dev;
struct urb_priv *urbp;
struct list_head remove_list; /* P: uhci->remove_list_lock */
struct list_head list; /* P: uhci->frame_list_lock */
} __attribute__((aligned(16)));
Then it works (tested 2 hours where as the original one hangs within the
minute with 2 USB keys). I just changed the position on the remove_list
field!
The hangs is in fact an endless loop inside free_pendings_qhs, because
one of the node of the list point to itself ( node->next = node).
I add dummy fields and move them a bit everywhere in the structure.
Theses fields are set on alloc_qh, modify on remove_qh. Then in
free_pending_qhs I check if the value set in remove_qh is "still there".
And it is all the time.
I try to put the dummies field at the place of the remove_list too: No
problem.
I have no idea why it works but it does...
I'm starting a night test anyway...Good night :-)
PS: My USB key will burn!
--
By the way, my USB floppy drive has a weird behavior on Linux, it's
detected as 6 or 8 devices. Well, I'll look into that then I will have
some free time!
Bye
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