diff mbox

[3/5] clk: mediatek: Add basic clocks for Mediatek MT8135.

Message ID 20150317094738.GF4927@pengutronix.de (mailing list archive)
State New, archived
Headers show

Commit Message

Sascha Hauer March 17, 2015, 9:47 a.m. UTC 
On Mon, Mar 16, 2015 at 08:03:39AM +0100, Uwe Kleine-König wrote:
> Hello Sascha,
> 
> On Mon, Mar 16, 2015 at 06:55:09AM +0100, Sascha Hauer wrote:
> > +static const char *axi_parents[] __initconst = {
> > +	"clk26m",
> > +	"syspll_d3",
> > +	"syspll_d4",
> > +	"syspll_d6",
> > +	"univpll_d5",
> > +	"univpll2_d2",
> > +	"syspll_d3p5"
> > +};
> __initconst should only be used for const data, but this array isn't
> const. Only the strings the pointer in this array point to are constant.

That may be true, but the way it's currently done compiles through
without warnings with CONFIG_DEBUG_SECTION_MISMATCH enabled.

> 
> So you have to use either
> 
> 	static const char *axi_parents[] __initdata = {

This results in:

drivers/clk/mediatek/clk-mt8173.c:515:20: error: i2s3_b_ck_parents causes a section type conflict with infra_clks
 static const char *i2s3_b_ck_parents[] __initdata = {

which can be avoided with static const char * const axi_parents[] __initdata

> 
> or
> 
> 	static const char * const axi_parents[] __initconst = {

Which results in:

drivers/clk/mediatek/clk-mt8173.c:568:2: warning: initialization discards 'const' qualifier from pointer target type
  MUX_GATE(TOP_HDCP_24M_SEL, "hdcp_24m_sel", hdcp_24m_parents, 0x00d0, 16, 2, 23),

With the following patch this can also be resolved. Until this is merged
(or I have the OK from Mike to add this in front of this series) I
prefer to keep it like it is at the moment.

(BTW I compile tested this with ARM multi_v7_defconfig, no additional
warnings are introduced with this patch)

Sascha

-------------------------------8<-----------------------------------

From 49f76867545d2f402c9684bb26339054b2151977 Mon Sep 17 00:00:00 2001
From: Sascha Hauer <s.hauer@pengutronix.de>
Date: Tue, 17 Mar 2015 10:43:41 +0100
Subject: [PATCH] clk: make initialization arrays const char * const *

Not only the initialization arrays should be const, but also the
strings inside the arrays. This allows users to put the parent_name
arrays into __initdata or __initconst.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 drivers/clk/clk-composite.c  | 2 +-
 drivers/clk/clk-mux.c        | 4 ++--
 include/linux/clk-provider.h | 8 ++++----
 3 files changed, 7 insertions(+), 7 deletions(-)

Comments

Uwe Kleine-König March 17, 2015, 1:54 p.m. UTC | #1 
Hello Sascha,

On Tue, Mar 17, 2015 at 10:47:38AM +0100, Sascha Hauer wrote:
> On Mon, Mar 16, 2015 at 08:03:39AM +0100, Uwe Kleine-König wrote:
> > On Mon, Mar 16, 2015 at 06:55:09AM +0100, Sascha Hauer wrote:
> > > +static const char *axi_parents[] __initconst = {
> > > +	"clk26m",
> > > +	"syspll_d3",
> > > +	"syspll_d4",
> > > +	"syspll_d6",
> > > +	"univpll_d5",
> > > +	"univpll2_d2",
> > > +	"syspll_d3p5"
> > > +};
> > __initconst should only be used for const data, but this array isn't
> > const. Only the strings the pointer in this array point to are constant.
> 
> That may be true, but the way it's currently done compiles through
> without warnings with CONFIG_DEBUG_SECTION_MISMATCH enabled.
CONFIG_DEBUG_SECTION_MISMATCH doesn't catch this type of error.

> 
> > 
> > So you have to use either
> > 
> > 	static const char *axi_parents[] __initdata = {
> 
> This results in:
> 
> drivers/clk/mediatek/clk-mt8173.c:515:20: error: i2s3_b_ck_parents causes a section type conflict with infra_clks
>  static const char *i2s3_b_ck_parents[] __initdata = {
The compiler catches if a single section contains both modifiable and
constant data. The linker doesn't seem to check anything here. So you
have to do it consistently per compilation unit. (I'm not aware of any
problems if you do it consistently wrong in a compilation unit, but
better do it consistently right :-)
I'm sure getting it right isn't that hard, so IMHO this should be fixed
before your patch is applied.

> which can be avoided with static const char * const axi_parents[] __initdata
This should be __initconst (to do it consistently right).

> > or
> > 
> > 	static const char * const axi_parents[] __initconst = {
> 
> Which results in:
> 
> drivers/clk/mediatek/clk-mt8173.c:568:2: warning: initialization discards 'const' qualifier from pointer target type
>   MUX_GATE(TOP_HDCP_24M_SEL, "hdcp_24m_sel", hdcp_24m_parents, 0x00d0, 16, 2, 23),
> 
> With the following patch this can also be resolved. Until this is merged
> (or I have the OK from Mike to add this in front of this series) I
> prefer to keep it like it is at the moment.
I remember trying something like that some time ago, but without
success. I didn't modify clk-composite.c but still I would be surprised
if it were that easy.

(The result were commits like 4a043d79dc2d and 145047de9940.)

Best regards
Uwe
diff mbox

Patch

diff --git a/drivers/clk/clk-composite.c b/drivers/clk/clk-composite.c
index 956b7e5..077f4c714 100644
--- a/drivers/clk/clk-composite.c
+++ b/drivers/clk/clk-composite.c
@@ -188,7 +188,7 @@  static void clk_composite_disable(struct clk_hw *hw)
 }
 
 struct clk *clk_register_composite(struct device *dev, const char *name,
-			const char **parent_names, int num_parents,
+			const char * const *parent_names, int num_parents,
 			struct clk_hw *mux_hw, const struct clk_ops *mux_ops,
 			struct clk_hw *rate_hw, const struct clk_ops *rate_ops,
 			struct clk_hw *gate_hw, const struct clk_ops *gate_ops,
diff --git a/drivers/clk/clk-mux.c b/drivers/clk/clk-mux.c
index 69a094c..1fa2a8d 100644
--- a/drivers/clk/clk-mux.c
+++ b/drivers/clk/clk-mux.c
@@ -114,7 +114,7 @@  const struct clk_ops clk_mux_ro_ops = {
 EXPORT_SYMBOL_GPL(clk_mux_ro_ops);
 
 struct clk *clk_register_mux_table(struct device *dev, const char *name,
-		const char **parent_names, u8 num_parents, unsigned long flags,
+		const char * const *parent_names, u8 num_parents, unsigned long flags,
 		void __iomem *reg, u8 shift, u32 mask,
 		u8 clk_mux_flags, u32 *table, spinlock_t *lock)
 {
@@ -166,7 +166,7 @@  struct clk *clk_register_mux_table(struct device *dev, const char *name,
 EXPORT_SYMBOL_GPL(clk_register_mux_table);
 
 struct clk *clk_register_mux(struct device *dev, const char *name,
-		const char **parent_names, u8 num_parents, unsigned long flags,
+		const char * const *parent_names, u8 num_parents, unsigned long flags,
 		void __iomem *reg, u8 shift, u8 width,
 		u8 clk_mux_flags, spinlock_t *lock)
 {
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 5591ea7..3bdae71 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -209,7 +209,7 @@  struct clk_ops {
 struct clk_init_data {
 	const char		*name;
 	const struct clk_ops	*ops;
-	const char		**parent_names;
+	const char * const	*parent_names;
 	u8			num_parents;
 	unsigned long		flags;
 };
@@ -426,12 +426,12 @@  extern const struct clk_ops clk_mux_ops;
 extern const struct clk_ops clk_mux_ro_ops;
 
 struct clk *clk_register_mux(struct device *dev, const char *name,
-		const char **parent_names, u8 num_parents, unsigned long flags,
+		const char * const *parent_names, u8 num_parents, unsigned long flags,
 		void __iomem *reg, u8 shift, u8 width,
 		u8 clk_mux_flags, spinlock_t *lock);
 
 struct clk *clk_register_mux_table(struct device *dev, const char *name,
-		const char **parent_names, u8 num_parents, unsigned long flags,
+		const char * const *parent_names, u8 num_parents, unsigned long flags,
 		void __iomem *reg, u8 shift, u32 mask,
 		u8 clk_mux_flags, u32 *table, spinlock_t *lock);
 
@@ -518,7 +518,7 @@  struct clk_composite {
 };
 
 struct clk *clk_register_composite(struct device *dev, const char *name,
-		const char **parent_names, int num_parents,
+		const char * const *parent_names, int num_parents,
 		struct clk_hw *mux_hw, const struct clk_ops *mux_ops,
 		struct clk_hw *rate_hw, const struct clk_ops *rate_ops,
 		struct clk_hw *gate_hw, const struct clk_ops *gate_ops,