staging: comedi: Add kernel config for default buffer sizes

Allow the default values for the module parameters for the default
initial buffer size and default maximum buffer size to be specified in
the kernel configuration.

I'm not sure what the defaults for the defaults for the defaults should
be, but 64 KiB seems to small, so I used values suggested by Bernd Porr,
which are 2048 KiB for the default initial buffer size and 20480 for the
default maximum buffer size.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Cc: Bernd Porr <berndporr@f2s.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/Kconfig b/drivers/staging/comedi/Kconfig
index 9037d02939ffae751eead2d8b0d9075f55257b77..a1cf0b04c16d45bdee5f0adc5a8e5850cc4dae73 100644 (file)
--- a/drivers/staging/comedi/Kconfig
+++ b/drivers/staging/comedi/Kconfig
@@ -14,6 +14,26 @@ config COMEDI_DEBUG
          This is an option for use by developers; most people should
          say N here. This enables comedi core and driver debugging.
 
+config COMEDI_DEFAULT_BUF_SIZE_KB
+       int "Comedi default initial asynchronous buffer size in KiB"
+       default "2048"
+       depends on COMEDI != n
+       ---help---
+         This is the default asynchronous buffer size which is used for
+         commands running in the background in kernel space.  This
+         defaults to 2048 KiB of memory so that a 16 channel card
+         running at 10 kHz has of 2-4 seconds of buffer.
+
+config COMEDI_DEFAULT_BUF_MAXSIZE_KB
+       int "Comedi default maximum asynchronous buffer size in KiB"
+       default "20480"
+       depends on COMEDI != n
+       ---help---
+         This is the default maximum asynchronous buffer size which can
+         be requested by a userspace program without root privileges.
+         This is set to 20480 KiB so that a fast I/O card with 16
+         channels running at 100 kHz has 2-4 seconds of buffer.
+
 menuconfig COMEDI_MISC_DRIVERS
        tristate "Comedi misc drivers"
        depends on COMEDI

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index ef7bbe41661451355acc59fa11ebbe7b19832ed7..3222ac6706b40abbe67b869680de7eb062b82dda 100644 (file)
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -55,9 +55,6 @@ MODULE_AUTHOR("http://www.comedi.org");
 MODULE_DESCRIPTION("Comedi core module");
 MODULE_LICENSE("GPL");
 
-#define DEFAULT_BUF_MAXSIZE_KB 64
-#define DEFAULT_BUF_SIZE_KB 64
-
 #ifdef CONFIG_COMEDI_DEBUG
 int comedi_debug;
 EXPORT_SYMBOL(comedi_debug);
@@ -78,17 +75,18 @@ MODULE_PARM_DESC(comedi_num_legacy_minors,
                 "number of comedi minor devices to reserve for non-auto-configured devices (default 0)"
                );
 
-unsigned int comedi_default_buf_size_kb = DEFAULT_BUF_SIZE_KB;
+unsigned int comedi_default_buf_size_kb = CONFIG_COMEDI_DEFAULT_BUF_SIZE_KB;
 module_param(comedi_default_buf_size_kb, uint, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(comedi_default_buf_size_kb,
                 "default asynchronous buffer size in KiB (default "
-                __MODULE_STRING(DEFAULT_BUF_SIZE_KB) ")");
+                __MODULE_STRING(CONFIG_COMEDI_DEFAULT_BUF_SIZE_KB) ")");
 
-unsigned int comedi_default_buf_maxsize_kb = DEFAULT_BUF_MAXSIZE_KB;
+unsigned int comedi_default_buf_maxsize_kb
+       = CONFIG_COMEDI_DEFAULT_BUF_MAXSIZE_KB;
 module_param(comedi_default_buf_maxsize_kb, uint, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(comedi_default_buf_maxsize_kb,
                 "default maximum size of asynchronous buffer in KiB (default "
-                __MODULE_STRING(DEFAULT_BUF_MAXSIZE_KB) ")");
+                __MODULE_STRING(CONFIG_COMEDI_DEFAULT_BUF_MAXSIZE_KB) ")");
 
 static DEFINE_SPINLOCK(comedi_file_info_table_lock);
 static struct comedi_device_file_info