[PATCH RFC] spi: Dont call prepare/unprepare transfer if not populated

[PATCH RFC] spi: Dont call prepare/unprepare transfer if not populated

[Shubhrajyoti D]

Currently the prepare/unprepare transfer are called unconditionally.
The assumption is that every driver using the spi core queue infrastructure
has to populate the prepare and unprepare functions. This encourages
drivers to populate empty functions to prevent crashing.
This patch prevents the call to prepare/unprepare if not populated.

Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>
---

 drivers/spi/spi.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 37c555e..30e114c 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -532,7 +532,7 @@ static void spi_pump_messages(struct kthread_work *work)
 	/* Lock queue and check for queue work */
 	spin_lock_irqsave(&master->queue_lock, flags);
 	if (list_empty(&master->queue) || !master->running) {
-		if (master->busy) {
+		if (master->busy &&  master->unprepare_transfer_hardware) {
 			ret = master->unprepare_transfer_hardware(master);
 			if (ret) {
 				spin_unlock_irqrestore(&master->queue_lock, flags);
@@ -562,7 +562,7 @@ static void spi_pump_messages(struct kthread_work *work)
 		master->busy = true;
 	spin_unlock_irqrestore(&master->queue_lock, flags);
 
-	if (!was_busy) {
+	if (!was_busy && master->prepare_transfer_hardware) {
 		ret = master->prepare_transfer_hardware(master);
 		if (ret) {
 			dev_err(&master->dev,
-- 
1.7.5.4

Re: [PATCH RFC] spi: Dont call prepare/unprepare transfer if not populated

[Linus Walleij]

On Thu, May 10, 2012 at 3:50 PM, Shubhrajyoti D <shubhrajyoti@ti.com> wrote:

> Currently the prepare/unprepare transfer are called unconditionally.
> The assumption is that every driver using the spi core queue infrastructure
> has to populate the prepare and unprepare functions. This encourages
> drivers to populate empty functions to prevent crashing.
> This patch prevents the call to prepare/unprepare if not populated.
>
> Cc: Linus Walleij <linus.walleij@linaro.org>
> Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>

Great!
Acked-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij

Re: [PATCH RFC] spi: Dont call prepare/unprepare transfer if not populated

[Grant Likely]

On Thu, 10 May 2012 16:01:27 +0200, Linus Walleij <linus.walleij@linaro.org> wrote:
> On Thu, May 10, 2012 at 3:50 PM, Shubhrajyoti D <shubhrajyoti@ti.com> wrote:
> 
> > Currently the prepare/unprepare transfer are called unconditionally.
> > The assumption is that every driver using the spi core queue infrastructure
> > has to populate the prepare and unprepare functions. This encourages
> > drivers to populate empty functions to prevent crashing.
> > This patch prevents the call to prepare/unprepare if not populated.
> >
> > Cc: Linus Walleij <linus.walleij@linaro.org>
> > Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>
> 
> Great!
> Acked-by: Linus Walleij <linus.walleij@linaro.org>

Applied, thanks (after fixing extra whitespace defect).

g.

Re: [PATCH RFC] spi: Dont call prepare/unprepare transfer if not populated

[Andrew Lunn]

On Thu, May 10, 2012 at 09:24:55PM -0600, Grant Likely wrote:
> On Thu, 10 May 2012 16:01:27 +0200, Linus Walleij <linus.walleij@linaro.org> wrote:
> > On Thu, May 10, 2012 at 3:50 PM, Shubhrajyoti D <shubhrajyoti@ti.com> wrote:
> > 
> > > Currently the prepare/unprepare transfer are called unconditionally.
> > > The assumption is that every driver using the spi core queue infrastructure
> > > has to populate the prepare and unprepare functions. This encourages
> > > drivers to populate empty functions to prevent crashing.
> > > This patch prevents the call to prepare/unprepare if not populated.
> > >
> > > Cc: Linus Walleij <linus.walleij@linaro.org>
> > > Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>
> > 
> > Great!
> > Acked-by: Linus Walleij <linus.walleij@linaro.org>
> 
> Applied, thanks (after fixing extra whitespace defect).

Hi Grant

Is this going to appear in linux-next soon? Can i depend on having
this patch for 3.5?

     Thanks
	Andrew

Re: [PATCH RFC] spi: Dont call prepare/unprepare transfer if not populated

[Grant Likely]

On Tue, 15 May 2012 21:58:01 +0200, Andrew Lunn <andrew@lunn.ch> wrote:
> On Thu, May 10, 2012 at 09:24:55PM -0600, Grant Likely wrote:
> > On Thu, 10 May 2012 16:01:27 +0200, Linus Walleij <linus.walleij@linaro.org> wrote:
> > > On Thu, May 10, 2012 at 3:50 PM, Shubhrajyoti D <shubhrajyoti@ti.com> wrote:
> > > 
> > > > Currently the prepare/unprepare transfer are called unconditionally.
> > > > The assumption is that every driver using the spi core queue infrastructure
> > > > has to populate the prepare and unprepare functions. This encourages
> > > > drivers to populate empty functions to prevent crashing.
> > > > This patch prevents the call to prepare/unprepare if not populated.
> > > >
> > > > Cc: Linus Walleij <linus.walleij@linaro.org>
> > > > Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>
> > > 
> > > Great!
> > > Acked-by: Linus Walleij <linus.walleij@linaro.org>
> > 
> > Applied, thanks (after fixing extra whitespace defect).
> 
> Hi Grant
> 
> Is this going to appear in linux-next soon? Can i depend on having
> this patch for 3.5?

It's pushed out now.

g.