Re: [U-Boot] [PATCH 5/5] arm: socfpga: implement proper peripheral reset

Sun, 27 Jan 2019 00:58:39 -0800 

Am 26.01.2019 um 10:00 schrieb Marek Vasut:

On 1/25/19 9:30 PM, Simon Goldschmidt wrote:

This commit removes ad-hoc reset handling for peripheral resets from SPL
for socfpga gen5.

This is done because as U-Boot drivers support reset handling by now.

For kernels that don't support taking peripherals out of reset that are
not enabled by U-Boot, a new Kconfig option "OLD_SOCFPGA_KERNEL_COMPAT"
is added, which keeps the old behaviour of just enabling all peripherals.

This new option is enabled by default for now, as even Linux 4.20 does
not support reset handling on all peripherals.

Signed-off-by: Simon Goldschmidt <[email protected]>


Well ew, don't we have some pre-linux-boot hook which could just flip
the reset register bits in one place ? And also, I'd prefer this to be
runtime-configurable, not compile-time configurable.
And this will be the biggest change for v2. It's also why I needed so long to send this series. What I sent in this version is how Tom said the same thing is being handled for mach-sunxi (Kconfig "OLD_SUNXI_KERNEL_COMPAT").
So if I remember your last mails about this topic, you'd prefer an environment variable with a callback that leads to enabling all peripherals just before jumping to Linux (yes, I'll find a hook for that). 

I see two problems here:
- enabling all peripherals will need to be the default for some time, until Linux supports reset handling in all drivers. How do you want to deal with that? - is this scheme used somewhere else for compatibility? I think it would make sense for multiple architectures to use the same way to handle such compatibility issues... 

Regards,
Simon




---

  arch/arm/mach-socfpga/Kconfig     | 10 ++++++++++
  arch/arm/mach-socfpga/misc_gen5.c |  2 ++
  arch/arm/mach-socfpga/spl_gen5.c  | 10 ++++++++++
  3 files changed, 22 insertions(+)

diff --git a/arch/arm/mach-socfpga/Kconfig b/arch/arm/mach-socfpga/Kconfig
index 5e87371f8c..89acced8d8 100644
--- a/arch/arm/mach-socfpga/Kconfig
+++ b/arch/arm/mach-socfpga/Kconfig
@@ -142,4 +142,14 @@ config SYS_CONFIG_NAME
        default "socfpga_stratix10_socdk" if TARGET_SOCFPGA_STRATIX10_SOCDK
        default "socfpga_vining_fpga" if TARGET_SOCFPGA_SAMTEC_VINING_FPGA
+config OLD_SOCFPGA_KERNEL_COMPAT 
+       bool "Enable workarounds for booting old kernels"
+       depends on TARGET_SOCFPGA_GEN5
+       default y
+       help
+         Set this to enable various workarounds for old kernels (e.g. take all
+         peripherals out of reset because old kernels cannot handle reset).
+         This results in sub-optimal settings for newer kernels, only enable
+         if needed.
+
  endif
diff --git a/arch/arm/mach-socfpga/misc_gen5.c 
b/arch/arm/mach-socfpga/misc_gen5.c
index 04f237d100..168669923e 100644
--- a/arch/arm/mach-socfpga/misc_gen5.c
+++ b/arch/arm/mach-socfpga/misc_gen5.c
@@ -243,6 +243,7 @@ int arch_early_init_r(void)
        /* Add device descriptor to FPGA device table */
        socfpga_fpga_add(&altera_fpga[0]);
+#ifdef CONFIG_OLD_SOCFPGA_KERNEL_COMPAT 
  #ifdef CONFIG_DESIGNWARE_SPI
        /* Get Designware SPI controller out of reset */
        socfpga_per_reset(SOCFPGA_RESET(SPIM0), 0);
@@ -252,6 +253,7 @@ int arch_early_init_r(void)
  #ifdef CONFIG_NAND_DENALI
        socfpga_per_reset(SOCFPGA_RESET(NAND), 0);
  #endif
+#endif /* CONFIG_OLD_SOCFPGA_KERNEL_COMPAT */
return 0; 
  }
diff --git a/arch/arm/mach-socfpga/spl_gen5.c b/arch/arm/mach-socfpga/spl_gen5.c
index f9bea892b1..19a211256d 100644
--- a/arch/arm/mach-socfpga/spl_gen5.c
+++ b/arch/arm/mach-socfpga/spl_gen5.c
@@ -35,16 +35,22 @@ u32 spl_boot_device(void)
                return BOOT_DEVICE_RAM;
        case 0x2:       /* NAND Flash (1.8V) */
        case 0x3:       /* NAND Flash (3.0V) */
+#ifdef CONFIG_OLD_SOCFPGA_KERNEL_COMPAT
                socfpga_per_reset(SOCFPGA_RESET(NAND), 0);
+#endif
                return BOOT_DEVICE_NAND;
        case 0x4:       /* SD/MMC External Transceiver (1.8V) */
        case 0x5:       /* SD/MMC Internal Transceiver (3.0V) */
+#ifdef CONFIG_OLD_SOCFPGA_KERNEL_COMPAT
                socfpga_per_reset(SOCFPGA_RESET(SDMMC), 0);
                socfpga_per_reset(SOCFPGA_RESET(DMA), 0);
+#endif
                return BOOT_DEVICE_MMC1;
        case 0x6:       /* QSPI Flash (1.8V) */
        case 0x7:       /* QSPI Flash (3.0V) */
+#ifdef CONFIG_OLD_SOCFPGA_KERNEL_COMPAT
                socfpga_per_reset(SOCFPGA_RESET(QSPI), 0);
+#endif
                return BOOT_DEVICE_SPI;
        default:
                printf("Invalid boot device (bsel=%08x)!\n", bsel);
@@ -98,7 +104,9 @@ void board_init_f(ulong dummy)
                socfpga_bridges_reset(1);
        }
+#ifdef CONFIG_OLD_SOCFPGA_KERNEL_COMPAT 
        socfpga_per_reset(SOCFPGA_RESET(UART0), 0);
+#endif
        socfpga_per_reset(SOCFPGA_RESET(OSC1TIMER0), 0);
timer_init(); 
@@ -122,9 +130,11 @@ void board_init_f(ulong dummy)
        sysmgr_pinmux_init();
        sysmgr_config_warmrstcfgio(0);
+#ifdef CONFIG_OLD_SOCFPGA_KERNEL_COMPAT 
        /* De-assert reset for peripherals and bridges based on handoff */
        reset_deassert_peripherals_handoff();
        socfpga_bridges_reset(0);
+#endif
debug("Unfreezing/Thaw all I/O banks\n"); 
        /* unfreeze / thaw all IO banks */






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