´╗┐For making things build again:

Acked-by: Mike Looijmans

I'd be interested in use-cases for having nvmem as a module, I cannot think of any.


I am working on splitting of_get_nvmem_mac_address(), by moving most of its
burden to the nvmem interface. Intend to create this "just give me my bytes" function in nvmem:

int of_nvmem_cell_read(struct device_node *np, const char *name,
                       void *buf, size_t bytes);

With that in place, of_get_nvmem_mac_address becomes a one-liner:

return of_nvmem_cell_read(np, "mac-address", addr, ETH_ALEN);

That would allow of_get_nvmem_mac_address to be inlined, and this would move the link issues into modules that actually use that function.

Which may still be very confusing, since it means that CONFIG_MACB=y with CONFIG_NVMEM=m will fail, but setting both to "y" or both to "m" will work. So that would introduce more build failures again, right?

--
Mike.


On 04-04-18 12:38, Arnd Bergmann wrote:
The new of_get_nvmem_mac_address() helper function causes a link error
with CONFIG_NVMEM=m:

drivers/of/of_net.o: In function `of_get_nvmem_mac_address':
of_net.c:(.text+0x168): undefined reference to `of_nvmem_cell_get'
of_net.c:(.text+0x19c): undefined reference to `nvmem_cell_read'
of_net.c:(.text+0x1a8): undefined reference to `nvmem_cell_put'

I could not come up with a good solution for this, as the code is always
built-in. Using an #if IS_REACHABLE() check around it would solve the
link time issue but then stop it from working in that configuration.
Making of_nvmem_cell_get() an inline function could also solve that, but
seems a bit ugly since it's somewhat larger than most inline functions,
and it would just bring that problem into the callers.  Splitting the
function into a separate file might be an alternative.

This uses the big hammer by making CONFIG_NVMEM itself a 'bool' symbol,
which avoids the problem entirely but makes the vmlinux larger for anyone
that might use NVMEM support but doesn't need it built-in otherwise.

Fixes: 9217e566bdee ("of_net: Implement of_get_nvmem_mac_address helper")
Cc: Mike Looijmans <mike.looijm...@topic.nl>
Cc: Florian Fainelli <f.faine...@gmail.com>
Cc: Andrew Lunn <and...@lunn.ch>
Cc: David S. Miller <da...@davemloft.net>
Cc: netdev@vger.kernel.org
Signed-off-by: Arnd Bergmann <a...@arndb.de>
---
The problem arrived through the networking tree, but it's now in
mainline, so the fix could go through either tree
---
  drivers/nvmem/Kconfig | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 5f9bc787d634..1090924efdb1 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -1,5 +1,5 @@
  menuconfig NVMEM
-       tristate "NVMEM Support"
+       bool "NVMEM Support"
        help
          Support for NVMEM(Non Volatile Memory) devices like EEPROM, EFUSES...



Kind regards,

Mike Looijmans
System Expert

TOPIC Products
Materiaalweg 4, NL-5681 RJ Best
Postbus 440, NL-5680 AK Best
Telefoon: +31 (0) 499 33 69 79
E-mail: mike.looijm...@topicproducts.com
Website: www.topicproducts.com

Please consider the environment before printing this e-mail



Reply via email to