[src/trunk]: src/sys/external/bsd/drm2/linux linux: Accept multipage segments...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/1176cc082cfd
branches:  trunk
changeset: 1028795:1176cc082cfd
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sun Dec 19 12:03:13 2021 +0000

description:
linux: Accept multipage segments in sg_alloc_table_from_bus_dmamem.

diffstat:

 sys/external/bsd/drm2/linux/linux_sg.c |  21 ++++++++++++++++++---
 1 files changed, 18 insertions(+), 3 deletions(-)

diffs (46 lines):

diff -r 048f04219023 -r 1176cc082cfd sys/external/bsd/drm2/linux/linux_sg.c
--- a/sys/external/bsd/drm2/linux/linux_sg.c    Sun Dec 19 12:03:05 2021 +0000
+++ b/sys/external/bsd/drm2/linux/linux_sg.c    Sun Dec 19 12:03:13 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: linux_sg.c,v 1.3 2021/12/19 11:38:04 riastradh Exp $   */
+/*     $NetBSD: linux_sg.c,v 1.4 2021/12/19 12:03:13 riastradh Exp $   */
 
 /*-
  * Copyright (c) 2021 The NetBSD Foundation, Inc.
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: linux_sg.c,v 1.3 2021/12/19 11:38:04 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux_sg.c,v 1.4 2021/12/19 12:03:13 riastradh Exp $");
 
 #include <sys/bus.h>
 #include <sys/errno.h>
@@ -87,11 +87,26 @@
 sg_alloc_table_from_bus_dmamem(struct sg_table *sgt, bus_dma_tag_t dmat,
     const bus_dma_segment_t *seg, int nseg, gfp_t gfp)
 {
+       int i, npgs = 0;
        int ret;
 
        KASSERT(nseg >= 1);
 
-       ret = sg_alloc_table(sgt, nseg, gfp);
+       /*
+        * Count the number of pages.  Some segments may span multiple
+        * contiguous pages.
+        */
+       for (i = 0; i < nseg; i++) {
+               bus_size_t len = seg[i].ds_len;
+               for (; len >= PAGE_SIZE; len -= PAGE_SIZE, npgs++) {
+                       if (npgs == INT_MAX)
+                               return -ENOMEM;
+               }
+               KASSERTMSG(len == 0, "misaligned segment length: %ju\n",
+                   (uintmax_t)seg[i].ds_len);
+       }
+
+       ret = sg_alloc_table(sgt, npgs, gfp);
        if (ret)
                return ret;