On Fri, 2010-08-27 at 11:24 +0200, Cousson, Benoit wrote:
> On 8/27/2010 4:29 AM, rockefeller wrote:
> > Hi Tony,
> > In the implementation of omap_mux_init_signal(char *muxname, int val)
> > in arch/arm/mach-omap2/mux.c, it will modify the muxname of
> > caller that passed in and not recover it, did you mean to implement
> > to do so?(I try to explain my point of view as 2 examples below).
>
> I'm not sure it was really done on purpose. It works today because none
> of the following cases are really happening.
>
> >
> > [Example 1]
> > For a XIP device(NOR type), a caller function might be codeed like
> > below:
> >
> > omap_mux_init_signal("muxname.mode7", 0xFFFF);
> >
> > and in this case, the string "muxname.mode7" might be a const string
> > and not be modified.
>
> That case seems to be a valid one.
>
> >
> > [Example 2]
> > For a NAND device, a caller might be coded like below:
> >
> > static char *pin_mux_name = "muxname.mode7";
> >
> > function1()
> > {
> > omap_mux_init_signal(pin_mux_name, 0xFFFF);
> > }
> >
> > function2()
> > {
> > omap_mux_init_signal(pin_mux_name, 0x0000);
> > }
> >
> > void main()
> > {
> > function1();
> > function2();
> > }
> >
> > Because "muxname.mode7" in in RAM is modifiable, after function call
> > to function1(), the *pine_mux_name will be "muxname" and therefore when
> > calls to function2() to try to set this pin in mode7 with value 0x0000
> > might be un-expected result.
>
> In theory the pin mux is done once at init time, so I'm not sure this
> case is supposed to happen. Is it a real case?
I just encountered the issue when I ported
http://dev.omapzoom.org/?p=modem-int/kernel.git;a=shortlog;h=refs/heads/xmm-3630
to Froyo(Android-2.6.32)
>
> Anyway, I think that a simple strlcpy(tmp, muxname, 32) in
> omap_mux_init_signal can fix it.
>
> Do you mind submitting a patch to fix that?
>
> Thanks,
> Benoit
I would like to introduce a new function omap_mux_name_strcmp() that
adapted from strcmp() as below and verified with android-2.6.32 and
it works fine.
diff --git a/arch/arm/mach-omap2/mux.c b/arch/arm/mach-omap2/mux.c
index 6c2f8f0..b61c24a 100644
--- a/arch/arm/mach-omap2/mux.c
+++ b/arch/arm/mach-omap2/mux.c
@@ -127,17 +127,34 @@ int __init omap_mux_init_gpio(int gpio, int val)
return 0;
}
+static int omap_mux_name_strcmp(const char * mux_name, const char
*mode_name)
+{
+ unsigned char c1, c2;
+
+ while (1) {
+ c1 = *mux_name++;
+ c2 = *mode_name++;
+ if (c1 != c2) {
+ if ((c1 == 0 && c2 == '.') || (c1 == '.' && c2
== 0))
+ break;
+ else
+ return c1 < c2 ? -1 : 1;
+ }
+ if (!c1)
+ break;
+ }
+ return 0;
+}
+
int __init omap_mux_init_signal(char *muxname, int val)
{
struct omap_mux_entry *e;
- char *m0_name = NULL, *mode_name = NULL;
+ char *mode_name = NULL;
int found = 0;
mode_name = strchr(muxname, '.');
if (mode_name) {
- *mode_name = '\0';
mode_name++;
- m0_name = muxname;
} else {
mode_name = muxname;
}
@@ -147,7 +164,7 @@ int __init omap_mux_init_signal(char *muxname, int
val)
char *m0_entry = m->muxnames[0];
int i;
- if (m0_name && strcmp(m0_name, m0_entry))
+ if (m0_entry && omap_mux_name_strcmp(muxname, m0_entry))
continue;
for (i = 0; i < OMAP_MUX_NR_MODES; i++) {
@@ -156,7 +173,7 @@ int __init omap_mux_init_signal(char *muxname, int
val)
if (!mode_cur)
continue;
- if (!strcmp(mode_name, mode_cur)) {
+ if (!omap_mux_name_strcmp(mode_name, mode_cur))
{
u16 old_mode;
u16 mux_mode;
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