On Thursday 10 February 2011 01:28 AM, Luis Rodriguez wrote:
On Wed, Feb 09, 2011 at 06:33:27AM -0800, Mohammed Shajakhan wrote:
From: Mohammed Shafi Shajakhan<mshajakhan@xxxxxxxxxxx>
The DMA latency issue is observed only in Intel pinetrail platforms but
in the driver we had a default PM-QOS value of 55. This caused
unnecessary power consumption and battery drain in other platforms.
Address this issue by disabling PM-QOS by default by setting it's value
as '0' and making code changes appropriately.This addresses the bug:
https://bugzilla.kernel.org/show_bug.cgi?id=27532
If the user sees some DMA latency issue he can still use the pmqos as a
module parameter to trade power for throughput as below:
sudo modprobe ath9k pmqos=55
How many times are we going to write some work around for some
platform unpatched BIOS bug ?
mcgrof@tux ~/wireless-testing (git::master)$ git grep pm_qos_update_request drivers/
drivers/net/e1000e/netdev.c: pm_qos_update_request(&adapter->netdev->pm_qos_req, 55);
drivers/net/e1000e/netdev.c: pm_qos_update_request(&adapter->netdev->pm_qos_req,
drivers/net/wireless/ath/ath9k/main.c: pm_qos_update_request(&sc->pm_qos_req, ath9k_pm_qos_value);
drivers/net/wireless/ath/ath9k/main.c: pm_qos_update_request(&sc->pm_qos_req, PM_QOS_DEFAULT_VALUE);
drivers/net/wireless/ipw2x00/ipw2100.c: pm_qos_update_request(&ipw2100_pm_qos_req, 175);
drivers/net/wireless/ipw2x00/ipw2100.c: pm_qos_update_request(&ipw2100_pm_qos_req, PM_QOS_DEFAULT_VALUE);
Can't we punt this crap to userspace?
Luis thanks for the script and sorry I missed it in the bugzilla. Luis I
agree these workarounds are better placed to be in user place and the
only thing is those have issues must be aware of the script.
I am ccing Senthil to have his views.
thanks,
shafi
http://www.kernel.org/pub/linux/kernel/people/mcgrof/scripts/cpudmalatency.c
Can distributions just autodetect this issue and call something like this?
Luis
Signed-off-by: Mohammed Shafi Shajakhan<mshajakhan@xxxxxxxxxxx>
---
drivers/net/wireless/ath/ath9k/ath9k.h | 4 +++-
drivers/net/wireless/ath/ath9k/init.c | 9 +++++----
drivers/net/wireless/ath/ath9k/main.c | 9 +++++----
3 files changed, 13 insertions(+), 9 deletions(-)
diff --git a/drivers/net/wireless/ath/ath9k/ath9k.h b/drivers/net/wireless/ath/ath9k/ath9k.h
index 9272278..55fcd01 100644
--- a/drivers/net/wireless/ath/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath/ath9k/ath9k.h
@@ -57,7 +57,9 @@ struct ath_node;
#define A_MAX(a, b) ((a)> (b) ? (a) : (b))
-#define ATH9K_PM_QOS_DEFAULT_VALUE 55
+/* By default PM QOS is disabled */
+#define ATH9K_PM_QOS_DEFAULT_VALUE 0
+
#define TSF_TO_TU(_h,_l) \
((((u32)(_h))<< 22) | (((u32)(_l))>> 10))
diff --git a/drivers/net/wireless/ath/ath9k/init.c b/drivers/net/wireless/ath/ath9k/init.c
index e5c1eea..658ea02 100644
--- a/drivers/net/wireless/ath/ath9k/init.c
+++ b/drivers/net/wireless/ath/ath9k/init.c
@@ -43,7 +43,7 @@ MODULE_PARM_DESC(btcoex_enable, "Enable wifi-BT coexistence");
int ath9k_pm_qos_value = ATH9K_PM_QOS_DEFAULT_VALUE;
module_param_named(pmqos, ath9k_pm_qos_value, int, S_IRUSR | S_IRGRP | S_IROTH);
-MODULE_PARM_DESC(pmqos, "User specified PM-QOS value");
+MODULE_PARM_DESC(pmqos, "User specified PM-QOS value, by default disabled");
bool is_ath9k_unloaded;
/* We use the hw_value as an index into our private channel structure */
@@ -759,8 +759,8 @@ int ath9k_init_device(u16 devid, struct ath_softc *sc, u16 subsysid,
ath_init_leds(sc);
ath_start_rfkill_poll(sc);
-
- pm_qos_add_request(&sc->pm_qos_req, PM_QOS_CPU_DMA_LATENCY,
+ if (ath9k_pm_qos_value)
+ pm_qos_add_request(&sc->pm_qos_req, PM_QOS_CPU_DMA_LATENCY,
PM_QOS_DEFAULT_VALUE);
return 0;
@@ -819,7 +819,8 @@ void ath9k_deinit_device(struct ath_softc *sc)
ath9k_ps_restore(sc);
ieee80211_unregister_hw(hw);
- pm_qos_remove_request(&sc->pm_qos_req);
+ if (ath9k_pm_qos_value)
+ pm_qos_remove_request(&sc->pm_qos_req);
ath_rx_cleanup(sc);
ath_tx_cleanup(sc);
ath9k_deinit_softc(sc);
diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index 4ed43b2..3855092 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -1119,9 +1119,10 @@ static int ath9k_start(struct ieee80211_hw *hw)
/* User has the option to provide pm-qos value as a module
* parameter rather than using the default value of
- * 'ATH9K_PM_QOS_DEFAULT_VALUE'.
+ * 'ATH9K_PM_QOS_DEFAULT_VALUE' which disables PM QOS.
*/
- pm_qos_update_request(&sc->pm_qos_req, ath9k_pm_qos_value);
+ if (ath9k_pm_qos_value)
+ pm_qos_update_request(&sc->pm_qos_req, ath9k_pm_qos_value);
if (ah->caps.pcie_lcr_extsync_en&& common->bus_ops->extn_synch_en)
common->bus_ops->extn_synch_en(common);
@@ -1266,8 +1267,8 @@ static void ath9k_stop(struct ieee80211_hw *hw)
ath_radio_disable(sc, hw);
sc->sc_flags |= SC_OP_INVALID;
-
- pm_qos_update_request(&sc->pm_qos_req, PM_QOS_DEFAULT_VALUE);
+ if (ath9k_pm_qos_value)
+ pm_qos_update_request(&sc->pm_qos_req, PM_QOS_DEFAULT_VALUE);
mutex_unlock(&sc->mutex);
--
1.7.0.4
.
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