USB: ehci saves some memory in ISO transfer descriptors (3b6fcfd0) · Commits · 戴 / test

In the EHCI driver, itd->usecs[8] is used in periodic_usecs(), indexed by uframe. For an ITD's unused uframes it is 0, else it contains the same value as itd->stream->usecs. To check if an ITD's uframe is used, we can instead test itd->hw_transaction[uframe]: if used, it will be nonzero no matter what endianess is used. This patch replaces those two uses, eliminates itd->usecs[], and saves eight bytes from each ITD. Signed-off-by:

Karsten Wiese <fzu@wemgehoertderstaat.de> Signed-off-by:

David Brownell <dbrownell@users.sourceforge.net> Signed-off-by:

Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/ehci-sched.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -119,7 +119,8 @@ periodic_usecs (struct ehci_hcd *ehci, unsigned frame, unsigned uframe)
		q = &q->fstn->fstn_next;
		break;
		case Q_TYPE_ITD:
		usecs += q->itd->usecs [uframe];
		if (q->itd->hw_transaction[uframe])
		usecs += q->itd->stream->usecs;
		hw_p = &q->itd->hw_next;
		q = &q->itd->itd_next;
		break;
		@@ -1536,7 +1537,6 @@ itd_link_urb (
		uframe = next_uframe & 0x07;
		frame = next_uframe >> 3;

		itd->usecs [uframe] = stream->usecs;
		itd_patch(ehci, itd, iso_sched, packet, uframe);

		next_uframe += stream->interval;

drivers/usb/host/ehci.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -602,7 +602,6 @@ struct ehci_itd {
		unsigned frame; /* where scheduled */
		unsigned pg;
		unsigned index[8]; /* in urb->iso_frame_desc */
		u8 usecs[8];
		} __attribute__ ((aligned (32)));

		/-------------------------------------------------------------------------/

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