Re: [PATCH] Documentation/firmware_class/firmware_sample_driver.c

Anders Blomdell
2007-06-29T17:50:22Z

Satyam Sharma wrote:
> Hi,
>
> [ It's good that you're trying to fix this, code in documentation should
> be setting standards, clearly. ]
>
> On 6/27/07, Anders Blomdell <anders.blomdell@control.lth.se> wrote:
>> [...]
>> Minor modifications to make the example load and unload without Oops
>> [...]
>> static int sample_init(void)
>> {
>> - device_initialize(&ghost_device);
>> + device_register(&ghost_device);
>> /* since there is no real hardware insertion I just call the
>> * sample probe functions here */
>> - sample_probe_specific();
>> + /* sample_probe_specific(); */
>> sample_probe_default();
>> - sample_probe_async();
>> + /*sample_probe_async();*/
>> return 0;
>> }
>
> But IMO the above functions should be *fixed* to work properly instead
> of simply commenting them out. If they are un-fixable, why even keep
> the broken code in that file (only to mislead readers in future?). You
> might as well remove those calls (and the function definitions) completely.
> Best would be to fix them, of course.
>
> My Rs. 0.02,
> Satyam

Signed-off-by: Anders Blomdell <anders.blomdell@control.lth.se>

Minor modifications to make the example load and unload without Oops, with
suggestions from Satyam Sharma incorporated.

This is what unpatched version generates with 2.6.21.3

kernel: Oops: 0000 [#2]
...
kernel: Call Trace:
kernel: [<c04ae541>] sysfs_create_dir+0x49/0x63
kernel: [<c04e76ae>] kobject_shadow_add+0xd5/0x17d
kernel: [<c04e7908>] kobject_set_name+0x2b/0x92
kernel: [<c0556444>] device_add+0x9a/0x58e
kernel: [<c0620b65>] klist_init+0x23/0x2e
kernel: [<c055bfee>] _request_firmware+0x116/0x29f
kernel: [<c062149f>] wait_for_completion+0x8b/0x93
kernel: [<c055c20b>] request_firmware+0xf/0x11
kernel: [<e09420d9>] sample_init+0x59/0xc0 [firmware_sample_driver]
kernel: [<c0446c92>] sys_init_module+0x16b7/0x17ee
kernel: [<c04294de>] printk+0x0/0x1f
kernel: [<c0488436>] mntput_no_expire+0x11/0x6e
kernel: [<c0404fa8>] syscall_call+0x7/0xb

diff -u Documentation/firmware_class/firmware_sample_driver.c
/tmp/fw/firmware_sample_driver.c
--- Documentation/firmware_class/firmware_sample_driver.c 2007-05-24
23:22:47.000000000 +0200
+++ /tmp/fw/firmware_sample_driver.c 2007-06-29 19:41:29.000000000 +0200
@@ -15,11 +15,16 @@

#include "linux/firmware.h"

+static void ghost_release(struct device *dev)
+{
+ printk(KERN_DEBUG "firmware_sample_driver: ghost_release\n");
+}
+
static struct device ghost_device = {
.bus_id = "ghost0",
+ .release = ghost_release
};

-
static void sample_firmware_load(char *firmware, int size)
{
u8 buf[size+1];
@@ -32,7 +37,7 @@
{
/* uses the default method to get the firmware */
const struct firmware *fw_entry;
- printk(KERN_INFO "firmware_sample_driver: a ghost device got inserted
:)\n");
+ printk(KERN_INFO "firmware_sample_driver SYNC:\n");

if(request_firmware(&fw_entry, "sample_driver_fw", &ghost_device)!=0)
{
@@ -47,27 +52,9 @@

/* finish setting up the device */
}
-static void sample_probe_specific(void)
-{
- /* Uses some specific hotplug support to get the firmware from
- * userspace directly into the hardware, or via some sysfs file */
-
- /* NOTE: This currently doesn't work */

- printk(KERN_INFO "firmware_sample_driver: a ghost device got inserted
:)\n");
+static char *context = "async context";

- if(request_firmware(NULL, "sample_driver_fw", &ghost_device)!=0)
- {
- printk(KERN_ERR
- "firmware_sample_driver: Firmware load failed\n");
- return;
- }
-
- /* request_firmware blocks until userspace finished, so at
- * this point the firmware should be already in the device */
-
- /* finish setting up the device */
-}
static void sample_probe_async_cont(const struct firmware *fw, void *context)
{
if(!fw){
@@ -76,7 +63,7 @@
return;
}

- printk(KERN_INFO "firmware_sample_driver: device pointer \"%s\"\n",
+ printk(KERN_INFO "firmware_sample_driver ASYNC: context \"%s\"\n",
(char *)context);
sample_firmware_load(fw->data, fw->size);
}
@@ -84,9 +71,9 @@
{
/* Let's say that I can't sleep */
int error;
- error = request_firmware_nowait (THIS_MODULE, FW_ACTION_NOHOTPLUG,
+ error = request_firmware_nowait (THIS_MODULE, FW_ACTION_HOTPLUG,
"sample_driver_fw", &ghost_device,
- "my device pointer",
+ context,
sample_probe_async_cont);
if(error){
printk(KERN_ERR
@@ -97,16 +84,18 @@

static int sample_init(void)
{
- device_initialize(&ghost_device);
+ int ret = device_register(&ghost_device);
+ if (ret == 0) {
/* since there is no real hardware insertion I just call the
* sample probe functions here */
- sample_probe_specific();
sample_probe_default();
sample_probe_async();
- return 0;
+ }
+ return ret;
}
static void __exit sample_exit(void)
{
+ device_unregister(&ghost_device);
}

module_init (sample_init);