[SRU][N][PATCH v2 0/1] i2c: tegra: Use internal reset when reset property is not available

[Abdur Rahman]

[Impact]

The latest Noble kernel throws warning on boot on Nvidia Grace Blackwell
and Grace Hopper machines. The warning is thrown when device_reset is called
on Tegra I2C device. This reset returns with error. The following is printed
in the boot log:
------------[ cut here ]------------
WARNING: CPU: 128 PID: 1248 at drivers/i2c/busses/i2c-tegra.c:622 tegra_i2c_init+0x2f4/0x3b8 [i2c_tegra]
Modules linked in: i2c_tegra(+) fjes(-) aes_neon_bs aes_neon_blk aes_ce_blk aes_ce_cipher
CPU: 128 PID: 1248 Comm: (udev-worker) Not tainted 6.8.0-100-generic #100-Ubuntu
Hardware name: Supermicro MBD-G1SMH/G1SMH, BIOS 2.1a 05/27/2025
pstate: 23400009 (nzCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : tegra_i2c_init+0x2f4/0x3b8 [i2c_tegra]
lr : tegra_i2c_init+0x34/0x3b8 [i2c_tegra]
sp : ffff80009a46b570
x29: ffff80009a46b570 x28: 0000000000000000 x27: 000000000000002c
x26: 0000000000000000 x25: 0000000000000000 x24: ffff10000c3b8068
x23: ffff00008dcecc10 x22: ffffffffffffffed x21: ffff00008dcecc00
x20: 0000000000000000 x19: ffff100015f65880 x18: ffff80009a3050c0
x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000000000 x9 : ffffba296d237dc0
x8 : ffff100008412d30 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000000
x2 : 0000000000000000 x1 : 0000000000000000 x0 : 00000000fffffffe
Call trace:
tegra_i2c_init+0x2f4/0x3b8 [i2c_tegra]
tegra_i2c_probe+0x400/0x7c8 [i2c_tegra]
platform_probe+0x74/0x118
really_probe+0x1c0/0x420
__driver_probe_device+0x94/0x1d8
driver_probe_device+0x48/0x188
__driver_attach+0x14c/0x2c8
bus_for_each_dev+0x88/0x110
driver_attach+0x30/0x60
bus_add_driver+0x17c/0x2e8
driver_register+0x68/0x178
__platform_driver_register+0x34/0x60
tegra_i2c_driver_init+0x2c/0xff8 [i2c_tegra]
do_one_initcall+0x64/0x3b8
do_init_module+0xa4/0x280
load_module+0x810/0x958
init_module_from_file+0x98/0x118
idempotent_init_module+0x200/0x308
__arm64_sys_finit_module+0x70/0xf8
invoke_syscall+0x7c/0x130
el0_svc_common.constprop.0+0x4c/0x140
do_el0_svc+0x28/0x58
el0_svc+0x40/0x1c0
el0t_64_sync_handler+0x148/0x158
el0t_64_sync+0x1b0/0x1b8
---[ end trace 0000000000000000 ]---

[Fix]

Clean upstream cherry pick:
635bf3c88533 ("i2c: tegra: Use internal reset when reset property is not available")

[Test Plan]

Compile Tested. Boot warning goes away.

[Where problems could occur]

The scope of this patch is fairly limited and only the systems with tegra i2c
devices can experience unexpected behavior.

[Other notes]

V2: added bug link

Akhil R (1):
  i2c: tegra: Use internal reset when reset property is not available

 drivers/i2c/busses/i2c-tegra.c | 44 +++++++++++++++++++++++++++++++++-
 1 file changed, 43 insertions(+), 1 deletion(-)

-- 
2.43.0