Re: [PATCH v2 2/2] firmware: arm_scmi: Support 'reg-io-width' property for shared memory

[Cristian Marussi <cristian.marussi@arm.com>]

On Fri, Aug 16, 2024 at 10:39:42AM -0700, Florian Fainelli wrote:
> On 8/16/24 10:02, Cristian Marussi wrote:
> > On Tue, Aug 13, 2024 at 11:07:47AM -0700, Florian Fainelli wrote:
> > > Some shared memory areas might only support a certain access width,
> > > such as 32-bit, which memcpy_{from,to}_io() does not adhere to at least
> > > on ARM64 by making both 8-bit and 64-bit accesses to such memory.
> > > 
> > > Update the shmem layer to support reading from and writing to such
> > > shared memory area using the specified I/O width in the Device Tree. The
> > > various transport layers making use of the shmem.c code are updated
> > > accordingly to pass the I/O accessors that they store.
> > > 
> > 
> > Hi Florian,
> > 

Hi,

> > I gave it ago at this on a JUNO regarding the mailbox/shmem transport
> > without any issue. I'll have a go later on an OPTEE/shmem scenario too.
> > 
> > This looks fundamentally good to me, since you moved all ops setup at
> > setup time and you keep the pointers per-channel instead of global...
> 
> Thanks!
>

[snip]
 
> > > +
> > 
> > There are a bunch of warn/errs from checkpatch --strict, beside the volatile
> > here and on the previous typedefs, also about args reuse and trailing semicolon
> > in these macros...
> 
> I don't think we can silence the volatile ones, checkpatch --strict did not
> complain about the typedefs in my case, what did it look like in yours?

...I dont get warns on new typedefs..only on volatile and macro args
reuse


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WARNING: Use of volatile is usually wrong: see Documentation/process/volatile-considered-harmful.rst
#36: FILE: drivers/firmware/arm_scmi/common.h:322:
+typedef void (*shmem_copy_toio_t)(volatile void __iomem *to, const void *from,

WARNING: Use of volatile is usually wrong: see Documentation/process/volatile-considered-harmful.rst
#38: FILE: drivers/firmware/arm_scmi/common.h:324:
+typedef void (*shmem_copy_fromio_t)(void *to, const volatile void __iomem *from,

CHECK: Macro argument reuse 'amt' - possible side-effects?
#94: FILE: drivers/firmware/arm_scmi/shmem.c:37:
+#define SHMEM_IO_OPS(w, s, amt)						\
+static inline void shmem_memcpy_fromio##s(void *to,			\
+					  const volatile void __iomem *from, \
+					  size_t count)			\
+{									\
+	while (count) {							\
+		*(u##s *)to = __raw_read##w(from);			\
+		from += amt;						\
+		to += amt;						\
+		count -= amt;						\
+	}								\
+}									\
+static inline void shmem_memcpy_toio##s(volatile void __iomem *to,	\
+					const void *from,		\
+					size_t count)			\
+{									\
+	while (count) {							\
+		__raw_write##w(*(u##s *)from, to);			\
+		from += amt;						\
+		to += amt;						\
+		count -= amt;						\
+	}								\
+}									\
+static struct scmi_shmem_io_ops shmem_io_ops##s = {			\
+	.fromio	= shmem_memcpy_fromio##s,				\
+	.toio	= shmem_memcpy_toio##s,					\
+};

WARNING: macros should not use a trailing semicolon
#94: FILE: drivers/firmware/arm_scmi/shmem.c:37:
+#define SHMEM_IO_OPS(w, s, amt)						\
+static inline void shmem_memcpy_fromio##s(void *to,			\
+					  const volatile void __iomem *from, \
+					  size_t count)			\
+{									\
+	while (count) {							\
+		*(u##s *)to = __raw_read##w(from);			\
+		from += amt;						\
+		to += amt;						\
+		count -= amt;						\
+	}								\
+}									\
+static inline void shmem_memcpy_toio##s(volatile void __iomem *to,	\
+					const void *from,		\
+					size_t count)			\
+{									\
+	while (count) {							\
+		__raw_write##w(*(u##s *)from, to);			\
+		from += amt;						\
+		to += amt;						\
+		count -= amt;						\
+	}								\
+}									\
+static struct scmi_shmem_io_ops shmem_io_ops##s = {			\
+	.fromio	= shmem_memcpy_fromio##s,				\
+	.toio	= shmem_memcpy_toio##s,					\
+};

WARNING: Use of volatile is usually wrong: see Documentation/process/volatile-considered-harmful.rst
#96: FILE: drivers/firmware/arm_scmi/shmem.c:39:
+					  const volatile void __iomem *from, \

WARNING: Use of volatile is usually wrong: see Documentation/process/volatile-considered-harmful.rst
#106: FILE: drivers/firmware/arm_scmi/shmem.c:49:
+static inline void shmem_memcpy_toio##s(volatile void __iomem *to,	\

WARNING: Use of volatile is usually wrong: see Documentation/process/volatile-considered-harmful.rst
#128: FILE: drivers/firmware/arm_scmi/shmem.c:71:
+				       const volatile void __iomem *from,

WARNING: Use of volatile is usually wrong: see Documentation/process/volatile-considered-harmful.rst
#134: FILE: drivers/firmware/arm_scmi/shmem.c:77:
+static inline void shmem_memcpy_toio(volatile void __iomem *to,

total: 0 errors, 7 warnings, 1 checks, 312 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

"[PATCH] firmware: arm_scmi: Support 'reg-io-width' property for" has style problems, please review.

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.

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