USB: EHCI: add native scatter-gather support

This patch (as1300) adds native scatter-gather support to ehci-hcd.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 2a3265087ef3fc2817f45fc91d70ab053369e38f..5859522d6edd9f0dde4fc8241d5398b0f4381698 100644 (file)
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -605,6 +605,8 @@ static int ehci_init(struct usb_hcd *hcd)
        }
        ehci->command = temp;
 
+       /* Accept arbitrarily long scatter-gather lists */
+       hcd->self.sg_tablesize = ~0;
        return 0;
 }
 

diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index 139a2cc3f6410a3381936d3820c0cb37030ef8c6..a427d3b0063468659bd73351ecf6aba86e9210fb 100644 (file)
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -616,9 +616,11 @@ qh_urb_transaction (
 ) {
        struct ehci_qtd         *qtd, *qtd_prev;
        dma_addr_t              buf;
-       int                     len, maxpacket;
+       int                     len, this_sg_len, maxpacket;
        int                     is_input;
        u32                     token;
+       int                     i;
+       struct scatterlist      *sg;
 
        /*
         * URBs map to sequences of QTDs:  one logical transaction
@@ -659,7 +661,20 @@ qh_urb_transaction (
        /*
         * data transfer stage:  buffer setup
         */
-       buf = urb->transfer_dma;
+       i = urb->num_sgs;
+       if (len > 0 && i > 0) {
+               sg = urb->sg->sg;
+               buf = sg_dma_address(sg);
+
+               /* urb->transfer_buffer_length may be smaller than the
+                * size of the scatterlist (or vice versa)
+                */
+               this_sg_len = min_t(int, sg_dma_len(sg), len);
+       } else {
+               sg = NULL;
+               buf = urb->transfer_dma;
+               this_sg_len = len;
+       }
 
        if (is_input)
                token |= (1 /* "in" */ << 8);
@@ -675,7 +690,9 @@ qh_urb_transaction (
        for (;;) {
                int this_qtd_len;
 
-               this_qtd_len = qtd_fill(ehci, qtd, buf, len, token, maxpacket);
+               this_qtd_len = qtd_fill(ehci, qtd, buf, this_sg_len, token,
+                               maxpacket);
+               this_sg_len -= this_qtd_len;
                len -= this_qtd_len;
                buf += this_qtd_len;
 
@@ -691,8 +708,13 @@ qh_urb_transaction (
                if ((maxpacket & (this_qtd_len + (maxpacket - 1))) == 0)
                        token ^= QTD_TOGGLE;
 
-               if (likely (len <= 0))
-                       break;
+               if (likely(this_sg_len <= 0)) {
+                       if (--i <= 0 || len <= 0)
+                               break;
+                       sg = sg_next(sg);
+                       buf = sg_dma_address(sg);
+                       this_sg_len = min_t(int, sg_dma_len(sg), len);
+               }
 
                qtd_prev = qtd;
                qtd = ehci_qtd_alloc (ehci, flags);