Messages in this thread |  | | From | Geert Uytterhoeven <> | | Date | Thu, 19 Dec 2024 16:11:59 +0100 | | Subject | Re: [PATCH RFT 0/6] serial: sh-sci: Fixes for earlycon and keep_bootcon |
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Hi Claudiu,
On Thu, Dec 5, 2024 at 9:39 AM Claudiu Beznea <claudiu.beznea@tuxon.dev> wrote: > On 04.12.2024 23:38, Wolfram Sang wrote: > >> in the following scenarios: > >> > >> 1/ "earlycon keep_bootcon" were present in bootargs > >> 2/ only "earlycon" was present in bootargs > >> 3/ none of the "earlycon" or "earlycon keep_bootcon" were present in > >> bootargs > > ... > >> Please give it a try on your devices as well. > > > > Will happily do so. Is there something to look for? Except for "it > > works"? > > As this code touches the earlycon functionality, of interest are the 3 > cases highlighted above: > > 1/ "earlycon keep_bootcon" are both present in bootargs > 2/ only "earlycon" is present in bootargs > 3/ none of the "earlycon" or "earlycon keep_bootcon" are present in > bootargs > > One other thing, that I was currently able to test only on RZ/G3S, is to > see how it behaves when the debug serial is described in DT with an alias > other than zero. E.g., on [1] the debug serial alias on RZ/G3S was changed > from 0 to 3. With the new alias (3) there were issues that I've tried to > fix with this series.
I gave this a try on Koelsch, which has two easily-accessible usb-serial ports, for all three cases above. Originally, I had CONFIG_VT_CONSOLE=y (tty0 takes over from earlycon rather early), but I had to disable that to exercise all code paths (ttySC0 takes over much later).
A. CONFIG_VT_CONSOLE=y: OK B. CONFIG_VT_CONSOLE=y earlycon: OK early_console_setup: mapbase 0x00000000e6e60000 earlycon: scif0 at MMIO 0x00000000e6e60000 (options '115200n8') printk: legacy bootconsole [scif0] enabled printk: legacy console [tty0] enabled printk: legacy bootconsole [scif0] disabled early_console_exit: Clearing sci_ports[0] C. CONFIG_VT_CONSOLE=n earlycon: OK early_console_setup: mapbase 0x00000000e6e60000 earlycon: scif0 at MMIO 0x00000000e6e60000 (options '115200n8') printk: legacy bootconsole [scif0] enabled printk: legacy console [ttySC0] enabled printk: legacy bootconsole [scif0] disabled early_console_exit: Not clearing sci_ports[0] D. CONFIG_VT_CONSOLE=y earlycon keep_bootcon: OK early_console_setup: mapbase 0x00000000e6e60000 earlycon: scif0 at MMIO 0x00000000e6e60000 (options '115200n8') printk: legacy bootconsole [scif0] enabled printk: legacy console [tty0] enabled
So all good, but note that these cases worked fine without your series, too.
The real troublesome cases involve using earlycon on a different serial port than serial0. As I don't have any Renesas boards where chosen/stdout-path does not use serial0, I tried exchanging the serial0 and serial1 DT aliases, and updating chosen/stdout-path accordingly.
E. CONFIG_VT_CONSOLE=y: OK F. CONFIG_VT_CONSOLE=y earlycon: OK early_console_setup: mapbase 0x00000000e6e60000 earlycon: scif0 at MMIO 0x00000000e6e60000 (options '115200n8') printk: legacy bootconsole [scif0] enabled printk: legacy console [tty0] enabled printk: legacy bootconsole [scif0] disabled early_console_exit: Clearing sci_ports[0] G. CONFIG_VT_CONSOLE=y earlycon keep_bootcon: SCIF1 missing early_console_setup: mapbase 0x00000000e6e60000 earlycon: scif0 at MMIO 0x00000000e6e60000 (options '115200n8') printk: legacy bootconsole [scif0] enabled printk: legacy console [tty0] enabled sh-sci e6e68000.serial: error -EBUSY: sci_port[0] is used by earlycon! H. CONFIG_VT_CONSOLE=n earlycon: SCIF1 missing early_console_setup: mapbase 0x00000000e6e60000 earlycon: scif0 at MMIO 0x00000000e6e60000 (options '115200n8') printk: legacy bootconsole [scif0] enabled printk: legacy console [ttySC1] enabled printk: legacy bootconsole [scif0] disabled early_console_exit: Not clearing sci_ports[0] sh-sci e6e68000.serial: error -EBUSY: sci_port[0] is used by earlycon!
Case G gives a missing SCIF1, because sci_port[0] is still used for earlycon, as expected. Case H also gives a missing SCIF1, but should succeed IMHO, as earlycon is no longer active. I think early_console_exit() should clear the earlycon flag regardless.
Note that before your series, cases E-F worked too, but cases G-H gave an initialized but broken SCIF1 instead.
Now, can we improve? - Can we use a proper id instead of zero for earlycon, e.g. sci_probe_earlyprintk() does fill in early_serial_console.index? - Alternatively, can we use a separate sci_port structure instead of abusing sci_ports[0]?
Thanks!
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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