Re: [PATCH] of: Fix comparison of "compatible" properties

[Michal Simek <monstr-pSz03upnqPeHXe+LvDLADg@public.gmane.org>]

Grant Likely wrote:
> Commit 7c7b60cb87547b1664a4385c187f029bf514a737
> "of: put default string compare and #a/s-cell values into common header"
> 
> Breaks various things on powerpc due to using strncasecmp instead of
> strcasecmp for comparing against "compatible" strings.
> 
> This causes things like the 4xx PCI code to fail miserably due to the
> partial matches in code like this:
> 
>        for_each_compatible_node(np, NULL, "ibm,plb-pcix")
>                ppc4xx_probe_pcix_bridge(np);
>        for_each_compatible_node(np, NULL, "ibm,plb-pci")
>                ppc4xx_probe_pci_bridge(np);
> 
> This reverts us to use strcasecmp. I do wonder why microblase and sparc
> want the partial matches though. For sparc it could be historical, but
> microblaze is probably doing the wrong thing so this patch also changes
> the microblaze behaviour to use not allow partial matches.  Michal will
> surely beat me over the head with a cluestick if I'm wrong, in which
> case I'll fix this patch.

No, you are correct. I don't want partial matches.

> 
> It's not quite right to do partial name match. Entries in a compatible
> list are meant to be matched whole. If a device is compatible with both
> "foo" and "foo1", then the device should have both strings in its
> "compatible" property.

Nice example. I have better one. Look at of_serial.c. ns16550a must be 
for partial matches before ns16550. :-)

	{ .type = "serial", .compatible = "ns16550a", .data = (void 
*)PORT_16550A, },
	{ .type = "serial", .compatible = "ns16550",  .data = (void 
*)PORT_16550, },

Acked-by: Michal Simek <monstr-pSz03upnqPeHXe+LvDLADg@public.gmane.org>

> 
> Signed-off-by: Benjamin Herrenschmidt <benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
>       (for patch description)
> Signed-off-by: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
> CC: David Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
> CC: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
> CC: Michal Simek <michal.simek-g5w7nrANp4BDPfheJLI6IQ@public.gmane.org>
> ---
> 
>  include/linux/of.h |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/include/linux/of.h b/include/linux/of.h
> index f6d9cbc..a367e19 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -127,7 +127,7 @@ static inline unsigned long of_read_ulong(const __be32 *cell, int size)
>  
>  /* Default string compare functions, Allow arch asm/prom.h to override */
>  #if !defined(of_compat_cmp)
> -#define of_compat_cmp(s1, s2, l)	strncasecmp((s1), (s2), (l))
> +#define of_compat_cmp(s1, s2, l)	strcasecmp((s1), (s2))
>  #define of_prop_cmp(s1, s2)		strcmp((s1), (s2))
>  #define of_node_cmp(s1, s2)		strcasecmp((s1), (s2))
>  #endif
> 


-- 
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/
Microblaze U-BOOT custodian