On 06/07/21, Ramon Fried wrote: > On Mon, Jul 5, 2021 at 3:19 PM Stephan Gerhold <step...@gerhold.net> wrote: > > > > According to arch/arm/lib/crt0_64.S, the BSS section is "UNAVAILABLE" > > and uninitialized before relocation. Also, it overlaps with the > > appended DTB before relocation, so writing data into a variable > > in the BSS section might corrupt the appended DTB. > > > > Unfortunately, pinctrl-apq8016.c and pinctrl-apq8096.c do place the > > "pin_name" variable in the BSS section (since it's uninitialized). > > It's also used before relocation, when setting up the pinctrl for > > the serial driver. > > > > On DB410c this causes "GPIO_5" to be written into some part of an > > appended DTB, e.g.: > > > > 80111820: edfe0dd0 9f100000 38000000 c00e0000 ...........8.... > > 80111830: 28000000 11000000 10000000 00000000 ...(............ > > 80111840: 4f495047 8800355f 00000000 00000000 GPIO_5.......... > > 80111850: 00000000 00000000 01000000 00000000 ................ > > 80111860: 03000000 04000000 00000000 02000000 ................ > > 80111870: 03000000 04000000 0f000000 02000000 ................ > > 80111880: 03000000 2d000000 1b000000 6c617551 .......-....Qual > > 80111890: 6d6d6f63 63655420 6c6f6e68 6569676f comm Technologie > > > > Depending on the part of the DTB that is corrupted this might not > > cause any problems, but it can also result in strange reboots > > without any serial output. > > > > Fortunately, in practice this does not cause issues on DB410c yet > > because board_fdt_blob_setup() in dragonboard410c.c currently > > overrides the appended DTB with the one passed by the previous > > bootloader (LK) (which does not get corrupted). > > > > DB820c does not have board_fdt_blob_setup() so I would expect it to > > be affected by this problem. Perhaps everyone was just fortunate to > > not compile an U-Boot configuration where the pin_name corrupts an > > important part of the DTB.
I'll try to confirm during the week. After Ramon's pinctrl changes db820c did indeed break - was able to test a few months back- but we didnt have a board to test back then (and nobody complained) will come back to you on this but from what you are saying, this is probably the fix we needed for db820c > > > > Make sure "pin_name" is explicitly placed in the .data section > > instead of .bss to fix this. > > > > Cc: Ramon Fried <rfried....@gmail.com> > > Signed-off-by: Stephan Gerhold <step...@gerhold.net> > > --- > > > > arch/arm/mach-snapdragon/pinctrl-apq8016.c | 3 +-- > > arch/arm/mach-snapdragon/pinctrl-apq8096.c | 2 +- > > 2 files changed, 2 insertions(+), 3 deletions(-) > > > > diff --git a/arch/arm/mach-snapdragon/pinctrl-apq8016.c > > b/arch/arm/mach-snapdragon/pinctrl-apq8016.c > > index 1042b564c3..70c0be0bca 100644 > > --- a/arch/arm/mach-snapdragon/pinctrl-apq8016.c > > +++ b/arch/arm/mach-snapdragon/pinctrl-apq8016.c > > @@ -10,7 +10,7 @@ > > #include <common.h> > > > > #define MAX_PIN_NAME_LEN 32 > > -static char pin_name[MAX_PIN_NAME_LEN]; > > +static char pin_name[MAX_PIN_NAME_LEN] __section(".data"); > > static const char * const msm_pinctrl_pins[] = { > > "SDC1_CLK", > > "SDC1_CMD", > > @@ -59,4 +59,3 @@ struct msm_pinctrl_data apq8016_data = { > > .get_function_mux = apq8016_get_function_mux, > > .get_pin_name = apq8016_get_pin_name, > > }; > > - > > diff --git a/arch/arm/mach-snapdragon/pinctrl-apq8096.c > > b/arch/arm/mach-snapdragon/pinctrl-apq8096.c > > index 20a71c319b..45462f01c2 100644 > > --- a/arch/arm/mach-snapdragon/pinctrl-apq8096.c > > +++ b/arch/arm/mach-snapdragon/pinctrl-apq8096.c > > @@ -10,7 +10,7 @@ > > #include <common.h> > > > > #define MAX_PIN_NAME_LEN 32 > > -static char pin_name[MAX_PIN_NAME_LEN]; > > +static char pin_name[MAX_PIN_NAME_LEN] __section(".data"); > > static const char * const msm_pinctrl_pins[] = { > > "SDC1_CLK", > > "SDC1_CMD", > > -- > > 2.32.0 > > > Reviewed-by: Ramon Fried <rfried....@gmail.com>