[PATCH 1/1] intel_ips -- ensure we do not enable gpu turbo mode without driver linkage

[Andy Whitcroft]

Both when polling the current turbo status (in poll_turbo_status mode)
and when handling thermal events (in ips_irq_handler) the current status
of GPU turbo is updated to match the hardware status. However if during
driver initialisation we were unable aquire linkage to the i915 driver
enabling GPU turbo will lead to an oops on the first attempt to determine
GPU busy status.

Ensure that we do not enable GPU turbo unless we have driver linkage.

BugLink: http://bugs.launchpad.net/bugs/632430
Cc: sta...@kernel.org
Signed-off-by: Andy Whitcroft <a...@canonical.com>
---
drivers/platform/x86/intel_ips.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/x86/intel_ips.c b/drivers/platform/x86/intel_ips.c
index afe82e5..3ca50b3 100644
--- a/drivers/platform/x86/intel_ips.c
+++ b/drivers/platform/x86/intel_ips.c
@@ -680,7 +680,8 @@ static void update_turbo_limits(struct ips_driver *ips)
u32 hts = thm_readl(THM_HTS);

ips->cpu_turbo_enabled = !(hts & HTS_PCTD_DIS);
- ips->gpu_turbo_enabled = !(hts & HTS_GTD_DIS);
+ if (ips->gpu_busy)
+ ips->gpu_turbo_enabled = !(hts & HTS_GTD_DIS);
ips->core_power_limit = thm_readw(THM_MPCPC);
ips->mch_power_limit = thm_readw(THM_MMGPC);
ips->mcp_temp_limit = thm_readw(THM_PTL);
@@ -1150,7 +1151,8 @@ static irqreturn_t ips_irq_handler(int irq, void *arg)
STS_GPL_SHIFT;
/* ignore EC CPU vs GPU pref */
ips->cpu_turbo_enabled = !(sts & STS_PCTD_DIS);
- ips->gpu_turbo_enabled = !(sts & STS_GTD_DIS);
+ if (ips->gpu_busy)
+ ips->gpu_turbo_enabled = !(sts & STS_GTD_DIS);
ips->mcp_temp_limit = (sts & STS_PTL_MASK) >>
STS_PTL_SHIFT;
ips->mcp_power_limit = (tc1 & STS_PPL_MASK) >>
--
1.7.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majo...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

[Jesse Barnes]

Looks good, thanks. Most of the performance upside is on the GPU, so
running without i915 is a shame, but we definitely shouldn't oops, so
this patch looks fine.

Acked-by: Jesse Barnes <jba...@virtuousgeek.org>

--
Jesse Barnes, Intel Open Source Technology Center