On Tue, 23 Aug 2005 10:52:15 -0400 (EDT), Alan Stern <[EMAIL PROTECTED]> wrote:

> Both are correct.  The difference is that currently usbmon is unable to 
> read data buffers that are DMA-mapped.

There's a patch to fix that (appended).

However, I wonder if this is necessary to write a special driver
for a scanner. I thought that SANE supported scanners successfuly
through the libusb.

-- Pete

diff -urpN -X dontdiff linux-2.6.13-rc6/drivers/usb/mon/Makefile 
linux-2.6.13-rc6-lem/drivers/usb/mon/Makefile
--- linux-2.6.13-rc6/drivers/usb/mon/Makefile   2005-08-14 20:57:43.000000000 
-0700
+++ linux-2.6.13-rc6-lem/drivers/usb/mon/Makefile       2005-08-15 
11:25:32.000000000 -0700
@@ -2,7 +2,7 @@
 # Makefile for USB Core files and filesystem
 #
 
-usbmon-objs    := mon_main.o mon_stat.o mon_text.o
+usbmon-objs    := mon_main.o mon_stat.o mon_text.o mon_dma.o
 
 # This does not use CONFIG_USB_MON because we want this to use a tristate.
 obj-$(CONFIG_USB)      += usbmon.o
diff -urpN -X dontdiff linux-2.6.13-rc6/drivers/usb/mon/mon_dma.c 
linux-2.6.13-rc6-lem/drivers/usb/mon/mon_dma.c
--- linux-2.6.13-rc6/drivers/usb/mon/mon_dma.c  1969-12-31 16:00:00.000000000 
-0800
+++ linux-2.6.13-rc6-lem/drivers/usb/mon/mon_dma.c      2005-08-15 
16:11:51.000000000 -0700
@@ -0,0 +1,55 @@
+/*
+ * The USB Monitor, inspired by Dave Harding's USBMon.
+ * 
+ * mon_dma.c: Library which snoops on DMA areas.
+ *
+ * Copyright (C) 2005 Pete Zaitcev ([EMAIL PROTECTED])
+ */
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/highmem.h>
+#include <asm/page.h>
+
+#include <linux/usb.h> /* Only needed for declarations in usb_mon.h */
+#include "usb_mon.h"
+
+#ifdef __i386__                /* CONFIG_ARCH_I386 does not exit */
+#define MON_HAS_UNMAP 1
+
+#define phys_to_page(phys)     pfn_to_page((phys) >> PAGE_SHIFT)
+
+char mon_dmapeek(unsigned char *dst, dma_addr_t dma_addr, int len)
+{
+       struct page *pg;
+       unsigned long flags;
+       unsigned char *map;
+       unsigned char *ptr;
+
+       /*
+        * On i386, a DMA handle is the "physical" address of a page.
+        * In other words, the bus address is equal to physical address.
+        * There is no IOMMU.
+        */
+       pg = phys_to_page(dma_addr);
+
+       /*
+        * We are called from hardware IRQs in case of callbacks.
+        * But we can be called from softirq or process context in case
+        * of submissions. In such case, we need to protect KM_IRQ0.
+        */
+       local_irq_save(flags);
+       map = kmap_atomic(pg, KM_IRQ0);
+       ptr = map + (dma_addr & (PAGE_SIZE-1));
+       memcpy(dst, ptr, len);
+       kunmap_atomic(map, KM_IRQ0);
+       local_irq_restore(flags);
+       return 0;
+}
+#endif /* __i386__ */
+
+#ifndef MON_HAS_UNMAP
+char mon_dmapeek(unsigned char *dst, dma_addr_t dma_addr, int len)
+{
+       return 'D';
+}
+#endif
diff -urpN -X dontdiff linux-2.6.13-rc6/drivers/usb/mon/mon_main.c 
linux-2.6.13-rc6-lem/drivers/usb/mon/mon_main.c
--- linux-2.6.13-rc6/drivers/usb/mon/mon_main.c 2005-06-17 12:48:29.000000000 
-0700
+++ linux-2.6.13-rc6-lem/drivers/usb/mon/mon_main.c     2005-08-15 
16:12:46.000000000 -0700
@@ -2,6 +2,8 @@
  * The USB Monitor, inspired by Dave Harding's USBMon.
  *
  * mon_main.c: Main file, module initiation and exit, registrations, etc.
+ *
+ * Copyright (C) 2005 Pete Zaitcev ([EMAIL PROTECTED])
  */
 
 #include <linux/kernel.h>
@@ -311,7 +313,7 @@ static int __init mon_init(void)
 
        mondir = debugfs_create_dir("usbmon", NULL);
        if (IS_ERR(mondir)) {
-               printk(KERN_NOTICE TAG ": debugs is not available\n");
+               printk(KERN_NOTICE TAG ": debugfs is not available\n");
                return -ENODEV;
        }
        if (mondir == NULL) {
diff -urpN -X dontdiff linux-2.6.13-rc6/drivers/usb/mon/mon_text.c 
linux-2.6.13-rc6-lem/drivers/usb/mon/mon_text.c
--- linux-2.6.13-rc6/drivers/usb/mon/mon_text.c 2005-08-14 20:57:43.000000000 
-0700
+++ linux-2.6.13-rc6-lem/drivers/usb/mon/mon_text.c     2005-08-15 
11:44:13.000000000 -0700
@@ -91,25 +91,11 @@ static inline char mon_text_get_data(str
     int len, char ev_type)
 {
        int pipe = urb->pipe;
-       unsigned char *data;
-
-       /*
-        * The check to see if it's safe to poke at data has an enormous
-        * number of corner cases, but it seems that the following is
-        * more or less safe.
-        *
-        * We do not even try to look transfer_buffer, because it can
-        * contain non-NULL garbage in case the upper level promised to
-        * set DMA for the HCD.
-        */
-       if (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)
-               return 'D';
 
        if (len <= 0)
                return 'L';
-
-       if ((data = urb->transfer_buffer) == NULL)
-               return 'Z';     /* '0' would be not as pretty. */
+       if (len >= DATA_MAX)
+               len = DATA_MAX;
 
        /*
         * Bulk is easy to shortcut reliably. 
@@ -126,8 +112,21 @@ static inline char mon_text_get_data(str
                }
        }
 
-       if (len >= DATA_MAX)
-               len = DATA_MAX;
+       /*
+        * The check to see if it's safe to poke at data has an enormous
+        * number of corner cases, but it seems that the following is
+        * more or less safe.
+        *
+        * We do not even try to look transfer_buffer, because it can
+        * contain non-NULL garbage in case the upper level promised to
+        * set DMA for the HCD.
+        */
+       if (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)
+               return mon_dmapeek(ep->data, urb->transfer_dma, len);
+
+       if (urb->transfer_buffer == NULL)
+               return 'Z';     /* '0' would be not as pretty. */
+
        memcpy(ep->data, urb->transfer_buffer, len);
        return 0;
 }
diff -urpN -X dontdiff linux-2.6.13-rc6/drivers/usb/mon/usb_mon.h 
linux-2.6.13-rc6-lem/drivers/usb/mon/usb_mon.h
--- linux-2.6.13-rc6/drivers/usb/mon/usb_mon.h  2005-06-17 12:48:29.000000000 
-0700
+++ linux-2.6.13-rc6-lem/drivers/usb/mon/usb_mon.h      2005-08-15 
16:12:42.000000000 -0700
@@ -1,5 +1,7 @@
 /*
  * The USB Monitor, inspired by Dave Harding's USBMon.
+ * 
+ * Copyright (C) 2005 Pete Zaitcev ([EMAIL PROTECTED])
  */
 
 #ifndef __USB_MON_H
@@ -43,6 +45,10 @@ struct mon_reader {
 void mon_reader_add(struct mon_bus *mbus, struct mon_reader *r);
 void mon_reader_del(struct mon_bus *mbus, struct mon_reader *r);
 
+/*
+ */
+extern char mon_dmapeek(unsigned char *dst, dma_addr_t dma_addr, int len);
+
 extern struct semaphore mon_lock;
 
 extern struct file_operations mon_fops_text;


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