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[PATCH] SPI: busnum == 0 needs to work

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We need to be able to have a "SPI bus 0" matching chip numbering; but
that number was wrongly used to flag dynamic allocation of a bus number.

This patch resolves that issue; now negative numbers trigger dynamic alloc.

It also updates the how-to-write-a-controller-driver overview to mention
this stuff.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
David Brownell
2006-04-03 15:49:04 -07:00
committed by Greg Kroah-Hartman
parent ccf77cc4af
commit a020ed7521
3 changed files with 38 additions and 6 deletions
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4
drivers/spi/spi.c
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@@ -395,7 +395,7 @@ EXPORT_SYMBOL_GPL(spi_alloc_master);
int __init_or_module
spi_register_master(struct spi_master *master)
{
static atomic_t dyn_bus_id = ATOMIC_INIT(0);
static atomic_t dyn_bus_id = ATOMIC_INIT((1<<16) - 1);
struct device *dev = master->cdev.dev;
int status = -ENODEV;
int dynamic = 0;
@@ -404,7 +404,7 @@ spi_register_master(struct spi_master *master)
return -ENODEV;
/* convention: dynamically assigned bus IDs count down from the max */
if (master->bus_num == 0) {
if (master->bus_num < 0) {
master->bus_num = atomic_dec_return(&dyn_bus_id);
dynamic = 1;
}