| Message ID | 20120904154533.1DC4AFAA0F@dev.laptop.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 09/04/2012 03:45 PM, Daniel Drake wrote: > As detailed in the thread titled "viafb PLL/clock tweaking causes XO-1.5 > instability," enabling or disabling the IGA1/IGA2 clocks causes occasional > stability problems during suspend/resume cycles on this platform. > > This is rather odd, as the documentation suggests that clocks have two > states (on/off) and the default (stable) configuration is configured to > enable the clock only when it is needed. However, explicitly enabling *or* > disabling the clock triggers this system instability, suggesting that there > is a 3rd state at play here. > > Leaving the clock enable/disable registers alone solves this problem. > This fixes spurious reboots during suspend/resume behaviour introduced by > commit b692a63a. > > Signed-off-by: Daniel Drake <dsd@laptop.org> Applied. Thanks for investigating it. I didn't have the time to look at it due to writing my thesis. Patch looks okay, at least it is a clean workaround. I did Cc stable when committing it to fix older releases. Thanks, Florian Tobias Schandinat > --- > drivers/video/via/via_clock.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/drivers/video/via/via_clock.c b/drivers/video/via/via_clock.c > index af8f26b..db1e392 100644 > --- a/drivers/video/via/via_clock.c > +++ b/drivers/video/via/via_clock.c > @@ -25,6 +25,7 @@ > > #include <linux/kernel.h> > #include <linux/via-core.h> > +#include <asm/olpc.h> > #include "via_clock.h" > #include "global.h" > #include "debug.h" > @@ -289,6 +290,10 @@ static void dummy_set_pll(struct via_pll_config config) > printk(KERN_INFO "Using undocumented set PLL.\n%s", via_slap); > } > > +static void noop_set_clock_state(u8 state) > +{ > +} > + > void via_clock_init(struct via_clock *clock, int gfx_chip) > { > switch (gfx_chip) { > @@ -346,4 +351,18 @@ void via_clock_init(struct via_clock *clock, int gfx_chip) > break; > > } > + > + if (machine_is_olpc()) { > + /* The OLPC XO-1.5 cannot suspend/resume reliably if the > + * IGA1/IGA2 clocks are set as on or off (memory rot > + * occasionally happens during suspend under such > + * configurations). > + * > + * The only known stable scenario is to leave this bits as-is, > + * which in their default states are documented to enable the > + * clock only when it is needed. > + */ > + clock->set_primary_clock_state = noop_set_clock_state; > + clock->set_secondary_clock_state = noop_set_clock_state; > + } > } -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/video/via/via_clock.c b/drivers/video/via/via_clock.c index af8f26b..db1e392 100644 --- a/drivers/video/via/via_clock.c +++ b/drivers/video/via/via_clock.c @@ -25,6 +25,7 @@ #include <linux/kernel.h> #include <linux/via-core.h> +#include <asm/olpc.h> #include "via_clock.h" #include "global.h" #include "debug.h" @@ -289,6 +290,10 @@ static void dummy_set_pll(struct via_pll_config config) printk(KERN_INFO "Using undocumented set PLL.\n%s", via_slap); } +static void noop_set_clock_state(u8 state) +{ +} + void via_clock_init(struct via_clock *clock, int gfx_chip) { switch (gfx_chip) { @@ -346,4 +351,18 @@ void via_clock_init(struct via_clock *clock, int gfx_chip) break; } + + if (machine_is_olpc()) { + /* The OLPC XO-1.5 cannot suspend/resume reliably if the + * IGA1/IGA2 clocks are set as on or off (memory rot + * occasionally happens during suspend under such + * configurations). + * + * The only known stable scenario is to leave this bits as-is, + * which in their default states are documented to enable the + * clock only when it is needed. + */ + clock->set_primary_clock_state = noop_set_clock_state; + clock->set_secondary_clock_state = noop_set_clock_state; + } }
As detailed in the thread titled "viafb PLL/clock tweaking causes XO-1.5 instability," enabling or disabling the IGA1/IGA2 clocks causes occasional stability problems during suspend/resume cycles on this platform. This is rather odd, as the documentation suggests that clocks have two states (on/off) and the default (stable) configuration is configured to enable the clock only when it is needed. However, explicitly enabling *or* disabling the clock triggers this system instability, suggesting that there is a 3rd state at play here. Leaving the clock enable/disable registers alone solves this problem. This fixes spurious reboots during suspend/resume behaviour introduced by commit b692a63a. Signed-off-by: Daniel Drake <dsd@laptop.org> --- drivers/video/via/via_clock.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)