Re: [PATCH] ARM: beaglebone: add delay in lowlevel.c

[Konstantin Kletschke <konstantin.kletschke@xxxxxxxxxxxxx>]

More like this?

On Wed, Jan 08, 2025 at 04:19:49PM +0100, Ahmad Fatoum wrote:
> 
> It would be nice to have the comment more verbose. e.g. that this issue
> was observed on new Seeed-produced BBBs is an intersting info IMO.

 arch/arm/boards/beaglebone/lowlevel.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/arm/boards/beaglebone/lowlevel.c b/arch/arm/boards/beaglebone/lowlevel.c
index 5dc49dfaaf..7dc338d03a 100644
--- a/arch/arm/boards/beaglebone/lowlevel.c
+++ b/arch/arm/boards/beaglebone/lowlevel.c
@@ -97,6 +97,12 @@ extern char __dtb_z_am335x_boneblack_start[];
 extern char __dtb_z_am335x_bone_common_start[];
 extern char __dtb_z_am335x_bone_start[];

+static void __udelay(int us)
+{
+        volatile int i;
+       for (i = 0; i < us; i++);
+}
+
 /**
  * @brief The basic entry point for board initialization.
  *
@@ -135,6 +141,12 @@ static noinline int beaglebone_sram_init(void)
        am33xx_enable_uart0_pin_mux();
        omap_debug_ll_init();
        putc_ll('>');
+       /*
+        * Some (~5%) Beaglebone Black received from SEEED in batches
+        * after autumn 2024 require a delay to be able to warm start
+        * after reset
+        */
+       __udelay(3000);

        barebox_arm_entry(0x80000000, sdram_size, fdt);
 }