From: Paul Walmsley <paul@pwsan.com> To: linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: "Tony Lindgren" <tony@atomide.com>, "Kevin Hilman" <khilman@ti.com>, "Benoît Cousson" <b-cousson@ti.com>, "Vaibhav Hiremath" <hvaibhav@ti.com> Subject: [PATCH 05/11] ARM: OMAP2+: hwmod code/data: fix 32K sync timer Date: Thu, 07 Jun 2012 00:13:10 -0600 [thread overview] Message-ID: <20120607061309.25532.13430.stgit@dusk> (raw) In-Reply-To: <20120607060901.25532.68354.stgit@dusk> Kevin discovered that commit c8d82ff68fb6873691536cf33021977efbf5593c ("ARM: OMAP2/3: hwmod data: Add 32k-sync timer data to hwmod database") broke CORE idle on OMAP3. This prevents device low power states. The root cause is that the 32K sync timer IP block does not support smart-idle mode[1], and so the hwmod code keeps the IP block in no-idle mode while it is active. This in turn prevents the WKUP clockdomain from transitioning to idle. There is a hardcoded sleep dependency that prevents the CORE_L3 and CORE_CM clockdomains from transitioning to idle when the WKUP clockdomain is active[2], so the chip cannot enter any device low power states. It turns out that there is no need to take the 32k sync timer out of idle. The IP block itself probably does not have any native idle handling at all, due to its simplicity. Furthermore, the PRCM will never request target idle for this IP block while the kernel is running, due to the sleep dependency that prevents the WKUP clockdomain from idling while the CORE_L3 clockdomain is active. So we can safely leave the 32k sync timer in target-no-idle mode, even while we continue to access it. This workaround is implemented by programming the force-idle mode for any IP block that only supports the force-idle and no-idle modes. If an IP block is ever released that doesn't support smart-idle and requires no-idle mode to be programmed while it's in use, we'll have to change this behavior. Another theoretically clean fix for this problem would be to implement PM runtime-based control for 32k sync timer accesses. These PM runtime calls would need to located in a custom clocksource, since the 32k sync timer is currently used as an MMIO clocksource. But in practice, there would be little benefit to doing so; and there would be some cost, due to the addition of unnecessary lines of code and the additional CPU overhead of the PM runtime and hwmod code - unnecessary in this case. Another possible fix would have been to modify the pm34xx.c code to force the IP block idle before entering WFI. But this would not have been an acceptable approach: we are trying to remove this type of centralized IP block idle control from the PM code. This patch is effectively a workaround for a hardware problem. A better hardware approach would have been to implement a smart-idle target idle mode for this IP block. The smart-idle mode in this case would behave identically to the force-idle mode. We consider the force-idle and no-idle target idle mode settings to be intended for debugging and automatic idle management bug workarounds only[4]. This patch is a collaboration between Kevin Hilman <khilman@ti.com> and Paul Walmsley <paul@pwsan.com>. References: 1. Table 16-96 "REG_32KSYNCNT_SYSCONFIG" of the OMAP34xx TRM Rev. ZU (SWPU223U), available from: http://www.ti.com/pdfs/wtbu/OMAP34x_ES3.1.x_PUBLIC_TRM_vzU.zip 2. Table 4-72 "Sleep Dependencies" of the OMAP34xx TRM Rev. ZU (SWPU223U) 3. ibid. 4. Section 3.1.1.1.2 "Module-Level Clock Management" of The OMAP4430 TRM Rev. vAA (SWPU231AA). Cc: Tony Lindgren <tony@atomide.com> Cc: Vaibhav Hiremath <hvaibhav@ti.com> Cc: Benoît Cousson <b-cousson@ti.com> Tested-by: Kevin Hilman <khilman@ti.com> Signed-off-by: Kevin Hilman <khilman@ti.com> Signed-off-by: Paul Walmsley <paul@pwsan.com> --- arch/arm/mach-omap2/omap_hwmod.c | 32 ++++++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-) diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c index b0d3064..6b4ae31 100644 --- a/arch/arm/mach-omap2/omap_hwmod.c +++ b/arch/arm/mach-omap2/omap_hwmod.c @@ -1124,10 +1124,12 @@ static struct omap_hwmod_addr_space * __init _find_mpu_rt_addr_space(struct omap * _enable_sysc - try to bring a module out of idle via OCP_SYSCONFIG * @oh: struct omap_hwmod * * - * If module is marked as SWSUP_SIDLE, force the module out of slave - * idle; otherwise, configure it for smart-idle. If module is marked - * as SWSUP_MSUSPEND, force the module out of master standby; - * otherwise, configure it for smart-standby. No return value. + * Ensure that the OCP_SYSCONFIG register for the IP block represented + * by @oh is set to indicate to the PRCM that the IP block is active. + * Usually this means placing the module into smart-idle mode and + * smart-standby, but if there is a bug in the automatic idle handling + * for the IP block, it may need to be placed into the force-idle or + * no-idle variants of these modes. No return value. */ static void _enable_sysc(struct omap_hwmod *oh) { @@ -1141,8 +1143,26 @@ static void _enable_sysc(struct omap_hwmod *oh) sf = oh->class->sysc->sysc_flags; if (sf & SYSC_HAS_SIDLEMODE) { - idlemode = (oh->flags & HWMOD_SWSUP_SIDLE) ? - HWMOD_IDLEMODE_NO : HWMOD_IDLEMODE_SMART; + if (oh->flags & HWMOD_SWSUP_SIDLE) { + /* + * IP blocks without smart idle should be left + * in force-idle. Currently this only applies + * to 32k sync "timer" which is guaranteed to + * be accessible when the kernel is running. + * HWMOD_SWSUP_IDLE must also be set on these + * IP blocks to indicate a hardware problem. + * XXX Not an ideal workaround. + */ + if (oh->class->sysc->idlemodes & + (SIDLE_NO | SIDLE_FORCE) && + !(oh->class->sysc->idlemodes & + (SIDLE_SMART || SIDLE_SMART_WKUP))) + idlemode = HWMOD_IDLEMODE_FORCE; + else + idlemode = HWMOD_IDLEMODE_NO; + } else { + idlemode = HWMOD_IDLEMODE_SMART; + } _set_slave_idlemode(oh, idlemode, &v); } -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
WARNING: multiple messages have this Message-ID (diff)
From: paul@pwsan.com (Paul Walmsley) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 05/11] ARM: OMAP2+: hwmod code/data: fix 32K sync timer Date: Thu, 07 Jun 2012 00:13:10 -0600 [thread overview] Message-ID: <20120607061309.25532.13430.stgit@dusk> (raw) In-Reply-To: <20120607060901.25532.68354.stgit@dusk> Kevin discovered that commit c8d82ff68fb6873691536cf33021977efbf5593c ("ARM: OMAP2/3: hwmod data: Add 32k-sync timer data to hwmod database") broke CORE idle on OMAP3. This prevents device low power states. The root cause is that the 32K sync timer IP block does not support smart-idle mode[1], and so the hwmod code keeps the IP block in no-idle mode while it is active. This in turn prevents the WKUP clockdomain from transitioning to idle. There is a hardcoded sleep dependency that prevents the CORE_L3 and CORE_CM clockdomains from transitioning to idle when the WKUP clockdomain is active[2], so the chip cannot enter any device low power states. It turns out that there is no need to take the 32k sync timer out of idle. The IP block itself probably does not have any native idle handling at all, due to its simplicity. Furthermore, the PRCM will never request target idle for this IP block while the kernel is running, due to the sleep dependency that prevents the WKUP clockdomain from idling while the CORE_L3 clockdomain is active. So we can safely leave the 32k sync timer in target-no-idle mode, even while we continue to access it. This workaround is implemented by programming the force-idle mode for any IP block that only supports the force-idle and no-idle modes. If an IP block is ever released that doesn't support smart-idle and requires no-idle mode to be programmed while it's in use, we'll have to change this behavior. Another theoretically clean fix for this problem would be to implement PM runtime-based control for 32k sync timer accesses. These PM runtime calls would need to located in a custom clocksource, since the 32k sync timer is currently used as an MMIO clocksource. But in practice, there would be little benefit to doing so; and there would be some cost, due to the addition of unnecessary lines of code and the additional CPU overhead of the PM runtime and hwmod code - unnecessary in this case. Another possible fix would have been to modify the pm34xx.c code to force the IP block idle before entering WFI. But this would not have been an acceptable approach: we are trying to remove this type of centralized IP block idle control from the PM code. This patch is effectively a workaround for a hardware problem. A better hardware approach would have been to implement a smart-idle target idle mode for this IP block. The smart-idle mode in this case would behave identically to the force-idle mode. We consider the force-idle and no-idle target idle mode settings to be intended for debugging and automatic idle management bug workarounds only[4]. This patch is a collaboration between Kevin Hilman <khilman@ti.com> and Paul Walmsley <paul@pwsan.com>. References: 1. Table 16-96 "REG_32KSYNCNT_SYSCONFIG" of the OMAP34xx TRM Rev. ZU (SWPU223U), available from: http://www.ti.com/pdfs/wtbu/OMAP34x_ES3.1.x_PUBLIC_TRM_vzU.zip 2. Table 4-72 "Sleep Dependencies" of the OMAP34xx TRM Rev. ZU (SWPU223U) 3. ibid. 4. Section 3.1.1.1.2 "Module-Level Clock Management" of The OMAP4430 TRM Rev. vAA (SWPU231AA). Cc: Tony Lindgren <tony@atomide.com> Cc: Vaibhav Hiremath <hvaibhav@ti.com> Cc: Beno?t Cousson <b-cousson@ti.com> Tested-by: Kevin Hilman <khilman@ti.com> Signed-off-by: Kevin Hilman <khilman@ti.com> Signed-off-by: Paul Walmsley <paul@pwsan.com> --- arch/arm/mach-omap2/omap_hwmod.c | 32 ++++++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-) diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c index b0d3064..6b4ae31 100644 --- a/arch/arm/mach-omap2/omap_hwmod.c +++ b/arch/arm/mach-omap2/omap_hwmod.c @@ -1124,10 +1124,12 @@ static struct omap_hwmod_addr_space * __init _find_mpu_rt_addr_space(struct omap * _enable_sysc - try to bring a module out of idle via OCP_SYSCONFIG * @oh: struct omap_hwmod * * - * If module is marked as SWSUP_SIDLE, force the module out of slave - * idle; otherwise, configure it for smart-idle. If module is marked - * as SWSUP_MSUSPEND, force the module out of master standby; - * otherwise, configure it for smart-standby. No return value. + * Ensure that the OCP_SYSCONFIG register for the IP block represented + * by @oh is set to indicate to the PRCM that the IP block is active. + * Usually this means placing the module into smart-idle mode and + * smart-standby, but if there is a bug in the automatic idle handling + * for the IP block, it may need to be placed into the force-idle or + * no-idle variants of these modes. No return value. */ static void _enable_sysc(struct omap_hwmod *oh) { @@ -1141,8 +1143,26 @@ static void _enable_sysc(struct omap_hwmod *oh) sf = oh->class->sysc->sysc_flags; if (sf & SYSC_HAS_SIDLEMODE) { - idlemode = (oh->flags & HWMOD_SWSUP_SIDLE) ? - HWMOD_IDLEMODE_NO : HWMOD_IDLEMODE_SMART; + if (oh->flags & HWMOD_SWSUP_SIDLE) { + /* + * IP blocks without smart idle should be left + * in force-idle. Currently this only applies + * to 32k sync "timer" which is guaranteed to + * be accessible when the kernel is running. + * HWMOD_SWSUP_IDLE must also be set on these + * IP blocks to indicate a hardware problem. + * XXX Not an ideal workaround. + */ + if (oh->class->sysc->idlemodes & + (SIDLE_NO | SIDLE_FORCE) && + !(oh->class->sysc->idlemodes & + (SIDLE_SMART || SIDLE_SMART_WKUP))) + idlemode = HWMOD_IDLEMODE_FORCE; + else + idlemode = HWMOD_IDLEMODE_NO; + } else { + idlemode = HWMOD_IDLEMODE_SMART; + } _set_slave_idlemode(oh, idlemode, &v); }
next prev parent reply other threads:[~2012-06-07 6:21 UTC|newest] Thread overview: 120+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-06-07 6:13 [PATCH 00/11] ARM: OMAP: core/hwmod: first set of fixes for 3.5-rc Paul Walmsley 2012-06-07 6:13 ` Paul Walmsley 2012-06-07 6:13 ` [PATCH 01/11] ARM: OMAP2+: hwmod: add setup_preprogram hook Paul Walmsley 2012-06-07 6:13 ` Paul Walmsley 2012-06-07 6:13 ` [PATCH 02/11] ARM: OMAP4+: AESS: enable internal auto-gating during initial setup Paul Walmsley 2012-06-07 6:13 ` Paul Walmsley 2012-06-07 7:19 ` Tony Lindgren 2012-06-07 7:19 ` Tony Lindgren 2012-06-07 7:31 ` Paul Walmsley 2012-06-07 7:31 ` Paul Walmsley 2012-06-07 7:48 ` Tony Lindgren 2012-06-07 7:48 ` Tony Lindgren 2012-06-07 10:45 ` Paul Walmsley 2012-06-07 10:45 ` Paul Walmsley 2012-06-07 11:08 ` Tony Lindgren 2012-06-07 11:08 ` Tony Lindgren 2012-06-07 6:13 ` [PATCH 03/11] ARM: OMAP4: hwmod data: add SL2IF hardreset line Paul Walmsley 2012-06-07 6:13 ` Paul Walmsley 2012-06-07 6:13 ` [PATCH 04/11] ARM: OMAP2+: usb_host_fs: add custom reset for usb_host_fs (fsusb) Paul Walmsley 2012-06-07 6:13 ` Paul Walmsley 2012-06-07 7:31 ` Tony Lindgren 2012-06-07 7:31 ` Tony Lindgren 2012-06-07 7:33 ` Felipe Balbi 2012-06-07 7:33 ` Felipe Balbi 2012-06-07 8:00 ` Tony Lindgren 2012-06-07 8:00 ` Tony Lindgren 2012-06-07 7:40 ` Paul Walmsley 2012-06-07 7:40 ` Paul Walmsley 2012-06-07 7:51 ` Tony Lindgren 2012-06-07 7:51 ` Tony Lindgren 2012-06-07 7:55 ` Felipe Balbi 2012-06-07 7:55 ` Felipe Balbi 2012-06-07 8:02 ` Cousson, Benoit 2012-06-07 8:02 ` Cousson, Benoit 2012-06-07 8:10 ` Tony Lindgren 2012-06-07 8:10 ` Tony Lindgren 2012-06-07 8:14 ` Felipe Balbi 2012-06-07 8:14 ` Felipe Balbi 2012-06-07 10:52 ` Paul Walmsley 2012-06-07 10:52 ` Paul Walmsley 2012-06-07 12:30 ` Cousson, Benoit 2012-06-07 12:30 ` Cousson, Benoit 2012-06-08 1:11 ` Paul Walmsley 2012-06-08 1:11 ` Paul Walmsley 2012-06-08 13:13 ` Cousson, Benoit 2012-06-08 13:13 ` Cousson, Benoit 2012-06-08 13:28 ` Paul Walmsley 2012-06-08 13:28 ` Paul Walmsley 2012-06-08 19:32 ` Hiremath, Vaibhav 2012-06-08 19:32 ` Hiremath, Vaibhav 2012-06-08 23:10 ` AM335x CPSW reset (was "RE: [PATCH 04/11] ARM: OMAP2+: usb_host_fs: add custom reset for usb_host_fs (fsusb)") Paul Walmsley 2012-06-08 23:10 ` Paul Walmsley 2012-06-09 8:39 ` Hiremath, Vaibhav 2012-06-09 8:39 ` Hiremath, Vaibhav 2012-06-09 16:05 ` Paul Walmsley 2012-06-09 16:05 ` Paul Walmsley 2012-06-11 6:15 ` [PATCH 04/11] ARM: OMAP2+: usb_host_fs: add custom reset for usb_host_fs (fsusb) Tony Lindgren 2012-06-11 6:15 ` Tony Lindgren 2012-06-11 8:04 ` Paul Walmsley 2012-06-11 8:04 ` Paul Walmsley 2012-06-11 9:24 ` Cousson, Benoit 2012-06-11 9:24 ` Cousson, Benoit 2012-06-11 16:20 ` Paul Walmsley 2012-06-11 16:20 ` Paul Walmsley 2012-06-07 10:20 ` Paul Walmsley 2012-06-07 10:20 ` Paul Walmsley 2012-06-07 10:52 ` Tony Lindgren 2012-06-07 10:52 ` Tony Lindgren 2012-06-07 22:05 ` Paul Walmsley 2012-06-07 22:05 ` Paul Walmsley 2012-06-08 6:38 ` Tony Lindgren 2012-06-08 6:38 ` Tony Lindgren 2012-06-09 1:31 ` Paul Walmsley 2012-06-09 1:31 ` Paul Walmsley 2012-06-11 6:21 ` Tony Lindgren 2012-06-11 6:21 ` Tony Lindgren 2012-06-07 6:13 ` Paul Walmsley [this message] 2012-06-07 6:13 ` [PATCH 05/11] ARM: OMAP2+: hwmod code/data: fix 32K sync timer Paul Walmsley 2012-06-07 6:59 ` Hiremath, Vaibhav 2012-06-07 6:59 ` Hiremath, Vaibhav 2012-06-07 7:08 ` Paul Walmsley 2012-06-07 7:08 ` Paul Walmsley 2012-06-07 18:09 ` Hiremath, Vaibhav 2012-06-07 18:09 ` Hiremath, Vaibhav 2012-06-07 20:03 ` Paul Walmsley 2012-06-07 20:03 ` Paul Walmsley 2012-06-08 19:10 ` Hiremath, Vaibhav 2012-06-08 19:10 ` Hiremath, Vaibhav 2012-06-11 9:12 ` Cousson, Benoit 2012-06-11 9:12 ` Cousson, Benoit 2012-06-08 13:22 ` Tero Kristo 2012-06-08 13:22 ` Tero Kristo 2012-06-08 23:18 ` Paul Walmsley 2012-06-08 23:18 ` Paul Walmsley 2012-06-07 6:13 ` [PATCH 06/11] ARM: OMAP4+: hwmod: fix issue causing IPs not going back to Smart-Standby Paul Walmsley 2012-06-07 6:13 ` Paul Walmsley 2012-06-07 6:13 ` [PATCH 07/11] ARM: OMAP: PM: Lock clocks list while generating summary Paul Walmsley 2012-06-07 6:13 ` Paul Walmsley 2012-06-07 6:13 ` [PATCH 08/11] ARM: OMAP2+: CM: increase the module disable timeout Paul Walmsley 2012-06-07 6:13 ` Paul Walmsley 2012-06-07 6:13 ` [PATCH 10/11] ARM: OMAP2+: hwmod: add flag to prevent hwmod code from touching IP block during init Paul Walmsley 2012-06-07 6:13 ` Paul Walmsley 2012-06-07 6:13 ` [PATCH 09/11] ARM: OMAP4: clock data: add clockdomains for clocks used as main clocks Paul Walmsley 2012-06-07 6:13 ` Paul Walmsley 2012-06-07 6:39 ` Rajendra Nayak 2012-06-07 6:39 ` Rajendra Nayak 2012-06-18 17:41 ` Paul Walmsley 2012-06-18 17:41 ` Paul Walmsley 2012-06-19 5:15 ` Rajendra Nayak 2012-06-19 5:15 ` Rajendra Nayak 2012-06-07 6:13 ` [PATCH 11/11] ARM: OMAP4: hwmod data: do not enable or reset the McPDM during kernel init Paul Walmsley 2012-06-07 6:13 ` Paul Walmsley 2012-06-08 13:30 ` [PATCH 00/11] ARM: OMAP: core/hwmod: first set of fixes for 3.5-rc Tero Kristo 2012-06-08 13:30 ` Tero Kristo 2012-06-09 1:15 ` Paul Walmsley 2012-06-09 1:15 ` Paul Walmsley 2012-06-13 23:55 ` Paul Walmsley 2012-06-13 23:55 ` Paul Walmsley 2012-06-14 7:36 ` Tero Kristo 2012-06-14 7:36 ` Tero Kristo
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