[PATCH] net/irda: add clk_prepare/clk_unprepare to pxaficp_ir

[PATCH] net/irda: add clk_prepare/clk_unprepare to pxaficp_ir

[Philipp Zabel]

This patch adds clk_prepare/clk_unprepare calls to the pxaficp_ir
driver by using the helper functions clk_prepare_enable and
clk_disable_unprepare.

Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Cc: Eric Miao <eric.y.miao@gmail.com>
Cc: Haojian Zhuang <haojian.zhuang@marvell.com>
Cc: Samuel Ortiz <samuel@sortiz.org>
---
 drivers/net/irda/pxaficp_ir.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/irda/pxaficp_ir.c b/drivers/net/irda/pxaficp_ir.c
index 81d5275..ff16daf 100644
--- a/drivers/net/irda/pxaficp_ir.c
+++ b/drivers/net/irda/pxaficp_ir.c
@@ -128,20 +128,20 @@ struct pxa_irda {
 static inline void pxa_irda_disable_clk(struct pxa_irda *si)
 {
 	if (si->cur_clk)
-		clk_disable(si->cur_clk);
+		clk_disable_unprepare(si->cur_clk);
 	si->cur_clk = NULL;
 }
 
 static inline void pxa_irda_enable_firclk(struct pxa_irda *si)
 {
 	si->cur_clk = si->fir_clk;
-	clk_enable(si->fir_clk);
+	clk_prepare_enable(si->fir_clk);
 }
 
 static inline void pxa_irda_enable_sirclk(struct pxa_irda *si)
 {
 	si->cur_clk = si->sir_clk;
-	clk_enable(si->sir_clk);
+	clk_prepare_enable(si->sir_clk);
 }
 
 
-- 
1.7.9.1

Re: [PATCH] net/irda: add clk_prepare/clk_unprepare to pxaficp_ir

[David Miller]

From: Philipp Zabel <philipp.zabel@gmail.com>
Date: Thu, 15 Mar 2012 19:19:29 +0100

> This patch adds clk_prepare/clk_unprepare calls to the pxaficp_ir
> driver by using the helper functions clk_prepare_enable and
> clk_disable_unprepare.
> 
> Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>

This is terrible.

So the problem was that clk_enable can't be invoked from atomic
context, because it wants to take a mutex for some implementation.

Therefore an existing routine with well defined semantics,
clk_enable(), was turned into a NOP.

And this silently breaks drivers.

Instead of silently breaking things, make direct
clk_enable()/clk_disable() invocations either result in a compile
error or a run-time BUG_ON().

There are other ways this could have been handled as well.

But just making clk_{enable,disable}() essentially stop working
was not a very good one at all.

I'll apply this patch to net-next, but I just wanted to point out
what an absolutely brain-dead way this was handled.

Re: [PATCH] net/irda: add clk_prepare/clk_unprepare to pxaficp_ir

[Philipp Zabel]

On Sat, Mar 17, 2012 at 7:10 AM, David Miller <davem@davemloft.net> wrote:
> From: Philipp Zabel <philipp.zabel@gmail.com>
> Date: Thu, 15 Mar 2012 19:19:29 +0100
>
>> This patch adds clk_prepare/clk_unprepare calls to the pxaficp_ir
>> driver by using the helper functions clk_prepare_enable and
>> clk_disable_unprepare.
>>
>> Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
>
> This is terrible.
>
> So the problem was that clk_enable can't be invoked from atomic
> context, because it wants to take a mutex for some implementation.
>
> Therefore an existing routine with well defined semantics,
> clk_enable(), was turned into a NOP.
>
> And this silently breaks drivers.
>
> Instead of silently breaking things, make direct
> clk_enable()/clk_disable() invocations either result in a compile
> error or a run-time BUG_ON().

I expect that anybody who turns clk_enable/clk_disable into
no-ops for their platform will be sensible enough to take care of this.
The common struct clk framework already keeps a prepare_count
variable and clk_enable does WARN_ON(clk->prepare_count == 0).

In case of PXA, it's the clk_prepare/clk_unprepare calls that are the
no-ops anyway, so thanks for applying.

regards
Philipp