[PATCH] clk: ti: fapll: fix address space warnings

[PATCH] clk: ti: fapll: fix address space warnings

[Ben Dooks]

Fix the following warnings from casting "void __iomem *" pointers
to u32 when using sparse:

drivers/clk/ti/fapll.c:583:13: warning: cast removes address space of expression
drivers/clk/ti/fapll.c:623:21: warning: cast removes address space of expression

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
---
Cc: Tero Kristo <t-kristo@ti.com>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: linux-omap@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-clk@vger.kernel.org
---
 drivers/clk/ti/fapll.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/ti/fapll.c b/drivers/clk/ti/fapll.c
index 66a0d0e..d765f4a 100644
--- a/drivers/clk/ti/fapll.c
+++ b/drivers/clk/ti/fapll.c
@@ -43,14 +43,14 @@
 #define to_synth(_hw)		container_of(_hw, struct fapll_synth, hw)
 
 /* The bypass bit is inverted on the ddr_pll.. */
-#define fapll_is_ddr_pll(va)	(((u32)(va) & 0xffff) == 0x0440)
+#define fapll_is_ddr_pll(va)	(((u32 __force)(va) & 0xffff) == 0x0440)
 
 /*
  * The audio_pll_clk1 input is hard wired to the 27MHz bypass clock,
  * and the audio_pll_clk1 synthesizer is hardwared to 32KiHz output.
  */
-#define is_ddr_pll_clk1(va)	(((u32)(va) & 0xffff) == 0x044c)
-#define is_audio_pll_clk1(va)	(((u32)(va) & 0xffff) == 0x04a8)
+#define is_ddr_pll_clk1(va)	(((u32 __force)(va) & 0xffff) == 0x044c)
+#define is_audio_pll_clk1(va)	(((u32 __force)(va) & 0xffff) == 0x04a8)
 
 /* Synthesizer divider register */
 #define SYNTH_LDMDIV1		BIT(8)
-- 
2.8.1

Re: [PATCH] clk: ti: fapll: fix address space warnings

[Russell King - ARM Linux]

On Tue, Jun 07, 2016 at 03:05:37PM +0100, Ben Dooks wrote:
> Fix the following warnings from casting "void __iomem *" pointers
> to u32 when using sparse:
> 
> drivers/clk/ti/fapll.c:583:13: warning: cast removes address space of expression
> drivers/clk/ti/fapll.c:623:21: warning: cast removes address space of expression

As a note of general principle, adding __force to casts is not the correct
way to solve these sparse warnings.

__force is supposed to be used in places which know that the cast is 100%
legitimate - in other words, architecture code removing the __iomem-ness
of the pointer so it can be dereferenced.  Sprinking the code with __force
to shut these warnings up doesn't actually help the cause.

> diff --git a/drivers/clk/ti/fapll.c b/drivers/clk/ti/fapll.c
> index 66a0d0e..d765f4a 100644
> --- a/drivers/clk/ti/fapll.c
> +++ b/drivers/clk/ti/fapll.c
> @@ -43,14 +43,14 @@
>  #define to_synth(_hw)		container_of(_hw, struct fapll_synth, hw)
>  
>  /* The bypass bit is inverted on the ddr_pll.. */
> -#define fapll_is_ddr_pll(va)	(((u32)(va) & 0xffff) == 0x0440)
> +#define fapll_is_ddr_pll(va)	(((u32 __force)(va) & 0xffff) == 0x0440)

This should be a cast to unsigned long, not u32.

>  
>  /*
>   * The audio_pll_clk1 input is hard wired to the 27MHz bypass clock,
>   * and the audio_pll_clk1 synthesizer is hardwared to 32KiHz output.
>   */
> -#define is_ddr_pll_clk1(va)	(((u32)(va) & 0xffff) == 0x044c)
> -#define is_audio_pll_clk1(va)	(((u32)(va) & 0xffff) == 0x04a8)
> +#define is_ddr_pll_clk1(va)	(((u32 __force)(va) & 0xffff) == 0x044c)
> +#define is_audio_pll_clk1(va)	(((u32 __force)(va) & 0xffff) == 0x04a8)

Ditto.

A cast from an __iomem pointer to unsigned long is permitted - no need
to use __force.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.