Re: [PATCH v7 13/13] tests/acceptance: console boot tests for quanta-gsj

[Havard Skinnemoen]

On Tue, Aug 11, 2020 at 8:26 PM Havard Skinnemoen
<hskinnemoen@google.com> wrote:
>
> On Tue, Aug 11, 2020 at 1:48 AM Philippe Mathieu-Daudé <f4bug@amsat.org> 
> wrote:
> > INTERRUPTED: Test interrupted by SIGTERM
> > Runner error occurred: Timeout reached
> > (240.45 s)
> >
> > Is that expected?
>
> I'm not sure why it only happens when running direct kernel boot with
> unoptimized qemu, but it seems a little happier if I enable a few more
> peripherals that I have queued up (sd, ehci, ohci and rng), though not
> enough.
>
> It still stalls for an awfully long time on "console: Run /init as
> init process" though. I'm not sure what it's doing there. With -O2 it
> only takes a couple of seconds to move on.

So it turns out that the kernel gets _really_ sluggish when skipping
the clock initialization normally done by the boot loader.

I changed the reset value of CLKSEL like this:

diff --git a/hw/misc/npcm7xx_clk.c b/hw/misc/npcm7xx_clk.c
index 21ab4200d1..5e9849410f 100644
--- a/hw/misc/npcm7xx_clk.c
+++ b/hw/misc/npcm7xx_clk.c
@@ -67,7 +67,7 @@ enum NPCM7xxCLKRegisters {
  */
 static const uint32_t cold_reset_values[NPCM7XX_CLK_NR_REGS] = {
     [NPCM7XX_CLK_CLKEN1]        = 0xffffffff,
-    [NPCM7XX_CLK_CLKSEL]        = 0x004aaaaa,
+    [NPCM7XX_CLK_CLKSEL]        = 0x004aaba9,
     [NPCM7XX_CLK_CLKDIV1]       = 0x5413f855,
     [NPCM7XX_CLK_PLLCON0]       = 0x00222101 | PLLCON_LOKI,
     [NPCM7XX_CLK_PLLCON1]       = 0x00202101 | PLLCON_LOKI,

which switches the CPU core and UART to run from PLL2 instead of
CLKREF (25 MHz).

With this change, the test passes without optimization:

 (02/19) 
tests/acceptance/boot_linux_console.py:BootLinuxConsole.test_arm_quanta_gsj_initrd:
PASS (39.62 s)

It doesn't look like this change hurts booting from the bootrom (IIUC
the nuvoton bootblock overwrites CLKSEL anyway), but it's not super
clean.

Perhaps I should make it conditional on kernel_filename being set? Or
would it be better to provide a write_board_setup hook for this?