[PATCH] spi_bitbang(): use overridable setup_transfer() method

A small bug-fix for spi_bitbang: it must always call the setup_transfer
function via the overridable pointer, not assume that its
spi_bitbang_setup_transfer is sufficient.  Otherwise, if all options in the
transfers are default (0), the overrided function will never be called.

Granted, the function replacing it must call spi_bitbang_setup_transfer,
but it might also have other important things to do, even if the second
argument (the spi_transfer) is NULL.  Tested together with the other
patches on the spi_crisv32_sser and spi_crisv32_gpio drivers (not yet in
the kernel, will IIUC be submitted as part of the usual
arch-maintainer-pushes).

Signed-off-by: Hans-Peter Nilsson <hp@axis.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/spi/spi_bitbang.c

@@ -210,7 +210,7 @@ int spi_bitbang_setup(struct spi_device *spi)
 	if (!cs->txrx_word)
 		return -EINVAL;
 
-	retval = spi_bitbang_setup_transfer(spi, NULL);
+	retval = bitbang->setup_transfer(spi, NULL);
 	if (retval < 0)
 		return retval;
 
@@ -442,9 +442,10 @@ EXPORT_SYMBOL_GPL(spi_bitbang_transfer);
  * hardware that basically exposes a shift register) or per-spi_transfer
  * (which takes better advantage of hardware like fifos or DMA engines).
  *
- * Drivers using per-word I/O loops should use (or call) spi_bitbang_setup and
- * spi_bitbang_cleanup to handle those spi master methods.  Those methods are
- * the defaults if the bitbang->txrx_bufs routine isn't initialized.
+ * Drivers using per-word I/O loops should use (or call) spi_bitbang_setup,
+ * spi_bitbang_cleanup and spi_bitbang_setup_transfer to handle those spi
+ * master methods.  Those methods are the defaults if the bitbang->txrx_bufs
+ * routine isn't initialized.
  *
  * This routine registers the spi_master, which will process requests in a
  * dedicated task, keeping IRQs unblocked most of the time.  To stop