This reverts commit eb9aecd9

The above patch is supposed to fix a register index error on mt2701. It
is not clear if the problem solved is a hang or just an invalid value
returned, my guess is the second. The patch introduces, though, a new
hang on MT8173 device making them unusable. So, seems reasonable, revert
the patch because introduces a worst issue.

The reason I send a revert instead of trying to fix the issue for MT8173
is because the information needed to fix the issue is in the datasheet
and is not public. So I am not really able to fix it.

Fixes the following bug when CONFIG_MTK_THERMAL is set on MT8173
devices.

[    2.222488] Unable to handle kernel paging request at virtual address ffff8000125f5001
[    2.230421] Mem abort info:
[    2.233207]   ESR = 0x96000021
[    2.236261]   EC = 0x25: DABT (current EL), IL = 32 bits
[    2.241571]   SET = 0, FnV = 0
[    2.244623]   EA = 0, S1PTW = 0
[    2.247762] Data abort info:
[    2.250640]   ISV = 0, ISS = 0x00000021
[    2.254473]   CM = 0, WnR = 0
[    2.257544] swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000041850000
[    2.264251] [ffff8000125f5001] pgd=000000013ffff003, pud=000000013fffe003, pmd=000000013fff9003, pte=006800001100b707
[    2.274867] Internal error: Oops: 96000021 [#1] PREEMPT SMP
[    2.280432] Modules linked in:
[    2.283483] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.7.0-rc6+ #162
[    2.289914] Hardware name: Google Elm (DT)
[    2.294003] pstate: 20000005 (nzCv daif -PAN -UAO)
[    2.298792] pc : mtk_read_temp+0xb8/0x1c8
[    2.302793] lr : mtk_read_temp+0x7c/0x1c8
[    2.306794] sp : ffff80001003b930
[    2.310100] x29: ffff80001003b930 x28: 0000000000000000
[    2.315404] x27: 0000000000000002 x26: ffff0000f9550b10
[    2.320709] x25: ffff0000f9550a80 x24: 0000000000000090
[    2.326014] x23: ffff80001003ba24 x22: 00000000610344c0
[    2.331318] x21: 0000000000002710 x20: 00000000000001f4
[    2.336622] x19: 0000000000030d40 x18: ffff800011742ec0
[    2.341926] x17: 0000000000000001 x16: 0000000000000001
[    2.347230] x15: ffffffffffffffff x14: ffffff0000000000
[    2.352535] x13: ffffffffffffffff x12: 0000000000000028
[    2.357839] x11: 0000000000000003 x10: ffff800011295ec8
[    2.363143] x9 : 000000000000291b x8 : 0000000000000002
[    2.368447] x7 : 00000000000000a8 x6 : 0000000000000004
[    2.373751] x5 : 0000000000000000 x4 : ffff800011295cb0
[    2.379055] x3 : 0000000000000002 x2 : ffff8000125f5001
[    2.384359] x1 : 0000000000000001 x0 : ffff0000f9550a80
[    2.389665] Call trace:
[    2.392105]  mtk_read_temp+0xb8/0x1c8
[    2.395760]  of_thermal_get_temp+0x2c/0x40
[    2.399849]  thermal_zone_get_temp+0x78/0x160
[    2.404198]  thermal_zone_device_update.part.0+0x3c/0x1f8
[    2.409589]  thermal_zone_device_update+0x34/0x48
[    2.414286]  of_thermal_set_mode+0x58/0x88
[    2.418375]  thermal_zone_of_sensor_register+0x1a8/0x1d8
[    2.423679]  devm_thermal_zone_of_sensor_register+0x64/0xb0
[    2.429242]  mtk_thermal_probe+0x690/0x7d0
[    2.433333]  platform_drv_probe+0x5c/0xb0
[    2.437335]  really_probe+0xe4/0x448
[    2.440901]  driver_probe_device+0xe8/0x140
[    2.445077]  device_driver_attach+0x7c/0x88
[    2.449252]  __driver_attach+0xac/0x178
[    2.453082]  bus_for_each_dev+0x78/0xc8
[    2.456909]  driver_attach+0x2c/0x38
[    2.460476]  bus_add_driver+0x14c/0x230
[    2.464304]  driver_register+0x6c/0x128
[    2.468131]  __platform_driver_register+0x50/0x60
[    2.472831]  mtk_thermal_driver_init+0x24/0x30
[    2.477268]  do_one_initcall+0x50/0x298
[    2.481098]  kernel_init_freeable+0x1ec/0x264
[    2.485450]  kernel_init+0x1c/0x110
[    2.488931]  ret_from_fork+0x10/0x1c
[    2.492502] Code: f9401081 f9400402 b8a67821 8b010042 (b9400042)
[    2.498599] ---[ end trace e43e3105ed27dc99 ]---
[    2.503367] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
[    2.511020] SMP: stopping secondary CPUs
[    2.514941] Kernel Offset: disabled
[    2.518421] CPU features: 0x090002,25006005
[    2.522595] Memory Limit: none
[    2.525644] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]--

Cc: Michael Kao <michael.kao@mediatek.com>
Fixes: eb9aecd9 ("thermal: mediatek: fix register index error")
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20200707103412.1010823-1-enric.balletbo@collabora.com