Some more comments.
On Wed, 13 Jan 2010, Reddy, Teerth wrote:
> From: Teerth Reddy <teerth@xxxxxx>
>
> This patch has the workaround for errata 1.176.
> In some cases, user is not able to access DDR memory after
> warm-reset.This situation occurs while the warm-reset
> happens during a read access to DDR memory. In that
> particular conditions, DDR memory does not respond to a
> corrupted read command due to the warm reset occurence but
> SDRC is waiting for read completion.SDRC is not sensitive to
> the warm reset, but the interconect is reset on the fly,
> thus causing a misalignment between SDRC logic, interconect
> logic and DDR memory state.
>
> Root cause description: A corrupted read transaction is
> issued to a closed row: (address0, bank0) instead of the
> expected read access, violating protocol.
>
> Failure signature: Once the failure occurs and system has
> restarted, memory content is not accessible.SDRC registers
> can be accessed successfully, until 1st access to memory
> location is performed. After 1st access to memory is done,
> SDRC is stuck.
>
> WORKAROUND
> Steps to perform before a SW reset is trigged, if user needs
> to generate a SW reset and keep DDR memory content:
> 1. Enable self-refresh on idle request
> 2. Put SDRC in idle
> 3. Wait until SDRC goes to idle
> 4. Generate SW reset
>
> Steps to perform after warm reset occurs:
> If HW warm reset is the source, apply below steps before
> any accesses to SDRAM:
> 1. Reset SMS and SDRC
> 2. Re-initialize SMS, SDRC and memory
>
> This would need the u-boot/x-loader workaround changes
> as well for the reboot to work correctly.
>
> Signed-off-by: Teerth Reddy <teerth@xxxxxx>
> ---
> arch/arm/mach-omap2/prcm.c | 9 +++--
> arch/arm/mach-omap2/sram34xx.S | 50 ++++++++++++++++++++++++++++++++
> arch/arm/plat-omap/include/plat/sram.h | 7 ++++
> arch/arm/plat-omap/sram.c | 19 ++++++++++++
> 4 files changed, 81 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/prcm.c b/arch/arm/mach-omap2/prcm.c
> index 3ea8177..d66711e 100644
> --- a/arch/arm/mach-omap2/prcm.c
> +++ b/arch/arm/mach-omap2/prcm.c
> @@ -26,6 +26,7 @@
> #include <plat/prcm.h>
> #include <plat/irqs.h>
> #include <plat/control.h>
> +#include <plat/sram.h>
>
> #include "clock.h"
> #include "cm.h"
> @@ -134,9 +135,10 @@ void omap_prcm_arch_reset(char mode)
> s16 prcm_offs;
> omap2_clk_prepare_for_reboot();
>
> - if (cpu_is_omap24xx())
> + if (cpu_is_omap24xx()) {
> prcm_offs = WKUP_MOD;
> - else if (cpu_is_omap34xx()) {
> + prm_set_mod_reg_bits(OMAP_RST_DPLL3, prcm_offs, RM_RSTCTRL);
> + } else if (cpu_is_omap34xx()) {
> u32 l;
>
> prcm_offs = OMAP3430_GR_MOD;
> @@ -147,10 +149,9 @@ void omap_prcm_arch_reset(char mode)
> * cf. OMAP34xx TRM, Initialization / Software Booting
> * Configuration. */
> omap_writel(l, OMAP343X_SCRATCHPAD + 4);
> + omap3_warmreset();
Please add a comment to indicate that this function does not return.
> } else
> WARN_ON(1);
> -
> - prm_set_mod_reg_bits(OMAP_RST_DPLL3, prcm_offs, RM_RSTCTRL);
> }
>
> static inline u32 __omap_prcm_read(void __iomem *base, s16 module, u16 reg)
> diff --git a/arch/arm/mach-omap2/sram34xx.S b/arch/arm/mach-omap2/sram34xx.S
> index de99ba2..6a425ca 100644
> --- a/arch/arm/mach-omap2/sram34xx.S
> +++ b/arch/arm/mach-omap2/sram34xx.S
> @@ -33,6 +33,8 @@
>
> #include "sdrc.h"
> #include "cm.h"
> +#include "prcm-common.h"
> +#include "prm.h"
>
> .text
>
> @@ -68,6 +70,9 @@
> /* CM_CLKSEL1_PLL bit settings */
> #define CORE_DPLL_CLKOUT_DIV_SHIFT 0x1b
>
> +/* PRM_RSTCTRL bit setting */
> +#define EN_DPLL3_RESET 0x4
> +
> /*
> * omap3_sram_configure_core_dpll - change DPLL3 M2 divider
> *
> @@ -313,3 +318,48 @@ core_m2_mask_val:
> ENTRY(omap3_sram_configure_core_dpll_sz)
> .word . - omap3_sram_configure_core_dpll
>
> +
> +/* omap3_sram_warmreset -
> + *
> + * Enable SDRC self refresh on idle request, put SDRC in idle,
> + * wait until SDRC goes to idle
> + * Enable DPLL3 reset bit in RM_RSTCTRL
> + */
This multi-line comment needs to be fixed to conform with CodingStyle as
mentioned in my previous comments.
> +
> +ENTRY(omap3_sram_warmreset)
> +sdram_in_selfrefresh1:
> + ldr r11, omap3_sdrc_power1 @ read the SDRC_POWER register
> + ldr r12, [r11] @ read the contents of SDRC_POWER
> + mov r9, r12 @ keep a copy of SDRC_POWER bits
> + orr r12, r12, #SRFRONIDLEREQ_MASK @ enable self refresh on idle
> + str r12, [r11] @ write back to SDRC_POWER register
> + ldr r12, [r11] @ posted-write barrier for SDRC
> + ldr r11, omap3_cm_iclken1_core1 @ read the CM_ICLKEN1_CORE reg
> + ldr r12, [r11]
> + bic r12, r12, #EN_SDRC_MASK @ disable iclk bit for SDRC
> + str r12, [r11]
> +wait_sdrc_idle2:
> + ldr r11, omap3_cm_idlest1_core1
> + ldr r12, [r11]
> + and r12, r12, #ST_SDRC_MASK @ check for SDRC idle
> + cmp r12, #ST_SDRC_MASK
> + bne wait_sdrc_idle2
> +osw_warm_reset:
> + ldr r11, omap3_reset_cntrl
> + ldr r12, [r11]
> + orr r12, r12, #EN_DPLL3_RESET @ Enable DPLL3 reset bit
> + str r12, [r11]
> +osw_loop:
> + b osw_loop
> +
> +omap3_reset_cntrl:
> + .word OMAP34XX_PRM_REGADDR(OMAP3430_GR_MOD, RM_RSTCTRL)
> +omap3_sdrc_power1:
> + .word OMAP34XX_SDRC_REGADDR(SDRC_POWER)
> +omap3_cm_idlest1_core1:
> + .word OMAP34XX_CM_REGADDR(CORE_MOD, CM_IDLEST)
> +omap3_cm_iclken1_core1:
> + .word OMAP34XX_CM_REGADDR(CORE_MOD, CM_ICLKEN1)
> +
> +ENTRY(omap3_sram_warmreset_sz)
> + .word . - omap3_sram_warmreset
> diff --git a/arch/arm/plat-omap/include/plat/sram.h b/arch/arm/plat-omap/include/plat/sram.h
> index 16a1b45..2393cbe 100644
> --- a/arch/arm/plat-omap/include/plat/sram.h
> +++ b/arch/arm/plat-omap/include/plat/sram.h
> @@ -27,6 +27,9 @@ extern u32 omap3_configure_core_dpll(
> u32 sdrc_actim_ctrl_b_0, u32 sdrc_mr_0,
> u32 sdrc_rfr_ctrl_1, u32 sdrc_actim_ctrl_a_1,
> u32 sdrc_actim_ctrl_b_1, u32 sdrc_mr_1);
> +
> +extern u32 omap3_warmreset(void);
This should be named 'omap3_sram_warmreset' to conform with the naming
style used by the rest of the file.
> +
> extern void omap3_sram_restore_context(void);
>
> /* Do not use these */
> @@ -69,6 +72,10 @@ extern u32 omap3_sram_configure_core_dpll(
> u32 sdrc_actim_ctrl_b_1, u32 sdrc_mr_1);
> extern unsigned long omap3_sram_configure_core_dpll_sz;
>
> +extern u32 omap3_sram_warmreset(void);
> +
> +extern unsigned long omap3_sram_warmreset_sz;
> +
> #ifdef CONFIG_PM
> extern void omap_push_sram_idle(void);
> #else
> diff --git a/arch/arm/plat-omap/sram.c b/arch/arm/plat-omap/sram.c
> index d8d5094..722154b 100644
> --- a/arch/arm/plat-omap/sram.c
> +++ b/arch/arm/plat-omap/sram.c
> @@ -410,6 +410,16 @@ u32 omap3_configure_core_dpll(u32 m2, u32 unlock_dll, u32 f, u32 inc,
> sdrc_actim_ctrl_b_1, sdrc_mr_1);
> }
>
> +/* Function for SDRC config for warm reset */
> +static u32 (*_omap3_sram_warmreset)(void);
> +
> +u32 omap3_warmreset()
See above re: naming style.
> +{
> + WARN_ON(!_omap3_sram_warmreset);
> +
> + return _omap3_sram_warmreset();
> +}
What value is this function supposed to return? Again from my previous
comments, this function has no return value. In fact it never returns at
all. So this should not be marked as returning u32.
> +
> #ifdef CONFIG_PM
> void omap3_sram_restore_context(void)
> {
> @@ -418,6 +428,10 @@ void omap3_sram_restore_context(void)
> _omap3_sram_configure_core_dpll =
> omap_sram_push(omap3_sram_configure_core_dpll,
> omap3_sram_configure_core_dpll_sz);
> + _omap3_sram_warmreset =
> + omap_sram_push(omap3_sram_warmreset,
> + omap3_sram_warmreset_sz);
Please fix the indent level on the above lines to ensure they are indented
past the start of the LHS of the expression.
> +
> omap_push_sram_idle();
> }
> #endif /* CONFIG_PM */
> @@ -427,6 +441,11 @@ int __init omap34xx_sram_init(void)
> _omap3_sram_configure_core_dpll =
> omap_sram_push(omap3_sram_configure_core_dpll,
> omap3_sram_configure_core_dpll_sz);
> +
> + _omap3_sram_warmreset =
> + omap_sram_push(omap3_sram_warmreset,
> + omap3_sram_warmreset_sz);
Please fix the indent level on the above lines to ensure they are indented
past the start of the LHS of the expression.
> +
> omap_push_sram_idle();
> return 0;
> }
>
- Paul
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