+ Mark
On 02/08/21 02:39PM, Tudor.Ambarus@microchip.com wrote:
On 8/2/21 4:24 PM, Rafał Miłecki wrote:
quoted
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Hi,
Hi, Rafał!
quoted
It seems that kernel 5.11 broke spi-nor on Broadcom Northstar (BCM5301X)
platforms.
The problem seems to be spi_nor_spimem_read_data() which calculates:
op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;
On Northstar this happens to be:
op.dummy.nbytes = (0 * 0) / 8;
That results in bcm_qspi_bspi_set_flex_mode() dividing by zero in the:
bpp |= (op->dummy.nbytes * 8) / op->dummy.buswidth;
Could you take a look at that issue, please?
GOOD 5.10.55
BAD 5.11.22
BAD 5.12.19
BAD 5.13.2
BAD 5.13.7
It's hard to guess. Would you please bisect and identify the commit that introduces
the regression?
I think the bug is pretty obvious here. op->dummy.buswidth is 0 when
there is no dummy phase, and that's why there is a division by zero. The
controller driver does not check if the dummy phase exists (by checking
op->dummy.nbytes) before performing the calculation. I saw a similar
patch posted for spi-cadence-quadspi.c [0]. The fix is obvious IMO.
BTW, I think this was introduced by 0e30f47232ab ("mtd: spi-nor: add
support for DTR protocol"). It set buswidths of non-existent phases to
0.
The main question is: do we want to keep the buswidth 0 when the dummy
phase does not exist? It seems to be tripping up controller drivers.
FWIW, I think we should keep it 0 since I think that when dummy.nbytes
== 0 the other fields should be "don't care". The responsibility should
lie on the controller driver to check this.
Thoughts?
[0] https://patchwork.kernel.org/project/spi-devel-general/patch/92eea403-9b21-2488-9cc1-664bee760c5e@nskint.co.jp/
Thanks,
ta
quoted
[ 1.075513] Division by zero in kernel.
[ 1.079354] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.13.7 #18
[ 1.085376] Hardware name: BCM5301X
[ 1.088873] [<c0108394>] (unwind_backtrace) from [<c010498c>] (show_stack+0x10/0x14)
[ 1.096666] [<c010498c>] (show_stack) from [<c0696470>] (dump_stack+0x94/0xa8)
[ 1.103926] [<c0696470>] (dump_stack) from [<c03e7f94>] (Ldiv0+0x8/0x10)
[ 1.110653] [<c03e7f94>] (Ldiv0) from [<c0699274>] (bcm_qspi_exec_mem_op+0x3e0/0x744)
[ 1.118512] [<c0699274>] (bcm_qspi_exec_mem_op) from [<c0698740>] (spi_mem_exec_op+0x184/0x4fc)
[ 1.127234] [<c0698740>] (spi_mem_exec_op) from [<c0698bac>] (spi_mem_dirmap_read+0xf4/0x1c8)
[ 1.135780] [<c0698bac>] (spi_mem_dirmap_read) from [<c0697d58>] (spi_nor_spimem_read_data+0x13c/0x1ec)
[ 1.145199] [<c0697d58>] (spi_nor_spimem_read_data) from [<c0498d60>] (spi_nor_read+0x16c/0x174)
[ 1.154008] [<c0498d60>] (spi_nor_read) from [<c04835d0>] (mtd_read_oob_std+0x9c/0xa4)
[ 1.161964] [<c04835d0>] (mtd_read_oob_std) from [<c04855d0>] (mtd_read_oob+0x84/0x148)
[ 1.169997] [<c04855d0>] (mtd_read_oob) from [<c04856f4>] (mtd_read+0x60/0x90)
[ 1.177237] [<c04856f4>] (mtd_read) from [<c048ab50>] (bcm47xxpart_parse+0x1d4/0x744)
[ 1.185089] [<c048ab50>] (bcm47xxpart_parse) from [<c0488568>] (parse_mtd_partitions+0x188/0x424)
[ 1.193985] [<c0488568>] (parse_mtd_partitions) from [<c0486018>] (mtd_device_parse_register+0x7c/0x1c0)
[ 1.203489] [<c0486018>] (mtd_device_parse_register) from [<c04998b8>] (spi_nor_probe+0x20c/0x2d0)
[ 1.212471] [<c04998b8>] (spi_nor_probe) from [<c046fbf8>] (really_probe+0xf0/0x4dc)
[ 1.220245] [<c046fbf8>] (really_probe) from [<c046dd40>] (bus_for_each_drv+0x80/0xd0)
[ 1.228184] [<c046dd40>] (bus_for_each_drv) from [<c04701d0>] (__device_attach+0xf8/0x15c)
[ 1.236468] [<c04701d0>] (__device_attach) from [<c046edd4>] (bus_probe_device+0x84/0x8c)
[ 1.244668] [<c046edd4>] (bus_probe_device) from [<c046c6c4>] (device_add+0x300/0x840)
[ 1.252606] [<c046c6c4>] (device_add) from [<c04b3dc4>] (spi_add_device+0x9c/0x164)
[ 1.260292] [<c04b3dc4>] (spi_add_device) from [<c04b482c>] (spi_register_controller+0x8ac/0xbc0)
[ 1.269187] [<c04b482c>] (spi_register_controller) from [<c04b7bd4>] (bcm_qspi_probe+0x600/0x700)
[ 1.278092] [<c04b7bd4>] (bcm_qspi_probe) from [<c0471d3c>] (platform_probe+0x48/0x8c)
[ 1.286030] [<c0471d3c>] (platform_probe) from [<c046fbf8>] (really_probe+0xf0/0x4dc)
[ 1.293880] [<c046fbf8>] (really_probe) from [<c04705dc>] (device_driver_attach+0xf0/0x100)
[ 1.302254] [<c04705dc>] (device_driver_attach) from [<c0470678>] (__driver_attach+0x8c/0x11c)
[ 1.310888] [<c0470678>] (__driver_attach) from [<c046dc74>] (bus_for_each_dev+0x74/0xc0)
[ 1.319086] [<c046dc74>] (bus_for_each_dev) from [<c046efc8>] (bus_add_driver+0xf4/0x1dc)
[ 1.327286] [<c046efc8>] (bus_add_driver) from [<c0470cdc>] (driver_register+0x88/0x118)
[ 1.335397] [<c0470cdc>] (driver_register) from [<c01016dc>] (do_one_initcall+0x54/0x1d0)
[ 1.343598] [<c01016dc>] (do_one_initcall) from [<c08010e8>] (kernel_init_freeable+0x244/0x2ac)
[ 1.352337] [<c08010e8>] (kernel_init_freeable) from [<c069a7c8>] (kernel_init+0x8/0x118)
[ 1.360536] [<c069a7c8>] (kernel_init) from [<c0100130>] (ret_from_fork+0x14/0x24)
[ 1.368125] Exception stack(0xc1035fb0 to 0xc1035ff8)
[ 1.373184] 5fa0: 00000000 00000000 00000000 00000000
[ 1.381384] 5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 1.389582] 5fe0: 00000000 00000000 00000000 00000000 00000013 00000000
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Regards,
Pratyush Yadav
Texas Instruments Inc.