From 2e18f5a1bc18e8af7031b3b26efde25307014837 Mon Sep 17 00:00:00 2001 From: Lokesh Vutla Date: Mon, 7 Mar 2016 01:41:21 -0700 Subject: ARM: OMAP2+: hwmod: Introduce ti,no-idle dt property Introduce a dt property, ti,no-idle, that prevents an IP to idle at any point. This is to handle Errata i877, which tells that GMAC clocks cannot be disabled. Acked-by: Roger Quadros Tested-by: Mugunthan V N Signed-off-by: Lokesh Vutla Signed-off-by: Sekhar Nori Signed-off-by: Dave Gerlach Acked-by: Rob Herring Cc: Signed-off-by: Paul Walmsley diff --git a/Documentation/devicetree/bindings/arm/omap/omap.txt b/Documentation/devicetree/bindings/arm/omap/omap.txt index a2bd593..66422d6 100644 --- a/Documentation/devicetree/bindings/arm/omap/omap.txt +++ b/Documentation/devicetree/bindings/arm/omap/omap.txt @@ -23,6 +23,7 @@ Optional properties: during suspend. - ti,no-reset-on-init: When present, the module should not be reset at init - ti,no-idle-on-init: When present, the module should not be idled at init +- ti,no-idle: When present, the module is never allowed to idle. Example: diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c index e9f65fe..b6d62e4 100644 --- a/arch/arm/mach-omap2/omap_hwmod.c +++ b/arch/arm/mach-omap2/omap_hwmod.c @@ -2200,6 +2200,11 @@ static int _enable(struct omap_hwmod *oh) */ static int _idle(struct omap_hwmod *oh) { + if (oh->flags & HWMOD_NO_IDLE) { + oh->_int_flags |= _HWMOD_SKIP_ENABLE; + return 0; + } + pr_debug("omap_hwmod: %s: idling\n", oh->name); if (oh->_state != _HWMOD_STATE_ENABLED) { @@ -2504,6 +2509,8 @@ static int __init _init(struct omap_hwmod *oh, void *data) oh->flags |= HWMOD_INIT_NO_RESET; if (of_find_property(np, "ti,no-idle-on-init", NULL)) oh->flags |= HWMOD_INIT_NO_IDLE; + if (of_find_property(np, "ti,no-idle", NULL)) + oh->flags |= HWMOD_NO_IDLE; } oh->_state = _HWMOD_STATE_INITIALIZED; @@ -2630,7 +2637,7 @@ static void __init _setup_postsetup(struct omap_hwmod *oh) * XXX HWMOD_INIT_NO_IDLE does not belong in hwmod data - * it should be set by the core code as a runtime flag during startup */ - if ((oh->flags & HWMOD_INIT_NO_IDLE) && + if ((oh->flags & (HWMOD_INIT_NO_IDLE | HWMOD_NO_IDLE)) && (postsetup_state == _HWMOD_STATE_IDLE)) { oh->_int_flags |= _HWMOD_SKIP_ENABLE; postsetup_state = _HWMOD_STATE_ENABLED; diff --git a/arch/arm/mach-omap2/omap_hwmod.h b/arch/arm/mach-omap2/omap_hwmod.h index 76bce11..7c7a311 100644 --- a/arch/arm/mach-omap2/omap_hwmod.h +++ b/arch/arm/mach-omap2/omap_hwmod.h @@ -525,6 +525,8 @@ struct omap_hwmod_omap4_prcm { * or idled. * HWMOD_OPT_CLKS_NEEDED: The optional clocks are needed for the module to * operate and they need to be handled at the same time as the main_clk. + * HWMOD_NO_IDLE: Do not idle the hwmod at all. Useful to handle certain + * IPs like CPSW on DRA7, where clocks to this module cannot be disabled. */ #define HWMOD_SWSUP_SIDLE (1 << 0) #define HWMOD_SWSUP_MSTANDBY (1 << 1) @@ -541,6 +543,7 @@ struct omap_hwmod_omap4_prcm { #define HWMOD_SWSUP_SIDLE_ACT (1 << 12) #define HWMOD_RECONFIG_IO_CHAIN (1 << 13) #define HWMOD_OPT_CLKS_NEEDED (1 << 14) +#define HWMOD_NO_IDLE (1 << 15) /* * omap_hwmod._int_flags definitions -- cgit v0.10.2 From 0f514e690740e54815441a87708c3326f8aa8709 Mon Sep 17 00:00:00 2001 From: Mugunthan V N Date: Mon, 7 Mar 2016 01:41:22 -0700 Subject: ARM: dts: dra7: do not gate cpsw clock due to errata i877 Errata id: i877 Description: ------------ The RGMII 1000 Mbps Transmit timing is based on the output clock (rgmiin_txc) being driven relative to the rising edge of an internal clock and the output control/data (rgmiin_txctl/txd) being driven relative to the falling edge of an internal clock source. If the internal clock source is allowed to be static low (i.e., disabled) for an extended period of time then when the clock is actually enabled the timing delta between the rising edge and falling edge can change over the lifetime of the device. This can result in the device switching characteristics degrading over time, and eventually failing to meet the Data Manual Delay Time/Skew specs. To maintain RGMII 1000 Mbps IO Timings, SW should minimize the duration that the Ethernet internal clock source is disabled. Note that the device reset state for the Ethernet clock is "disabled". Other RGMII modes (10 Mbps, 100Mbps) are not affected Workaround: ----------- If the SoC Ethernet interface(s) are used in RGMII mode at 1000 Mbps, SW should minimize the time the Ethernet internal clock source is disabled to a maximum of 200 hours in a device life cycle. This is done by enabling the clock as early as possible in IPL (QNX) or SPL/u-boot (Linux/Android) by setting the register CM_GMAC_CLKSTCTRL[1:0]CLKTRCTRL = 0x2:SW_WKUP. So, do not allow to gate the cpsw clocks using ti,no-idle property in cpsw node assuming 1000 Mbps is being used all the time. If someone does not need 1000 Mbps and wants to gate clocks to cpsw, this property needs to be deleted in their respective board files. Signed-off-by: Mugunthan V N Signed-off-by: Grygorii Strashko Signed-off-by: Lokesh Vutla Cc: Signed-off-by: Paul Walmsley diff --git a/arch/arm/boot/dts/dra7.dtsi b/arch/arm/boot/dts/dra7.dtsi index c4d9175..f82aa44 100644 --- a/arch/arm/boot/dts/dra7.dtsi +++ b/arch/arm/boot/dts/dra7.dtsi @@ -1500,6 +1500,16 @@ 0x48485200 0x2E00>; #address-cells = <1>; #size-cells = <1>; + + /* + * Do not allow gating of cpsw clock as workaround + * for errata i877. Keeping internal clock disabled + * causes the device switching characteristics + * to degrade over time and eventually fail to meet + * the data manual delay time/skew specs. + */ + ti,no-idle; + /* * rx_thresh_pend * rx_pend -- cgit v0.10.2