Re: [PATCH] spi: Fix SPI_CS_HIGH setting when using native and GPIO CS

From: Jon Hunter
Date: Thu Oct 24 2019 - 10:47:03 EST



On 18/10/2019 16:29, Gregory CLEMENT wrote:
> When improving the CS GPIO support at core level, the SPI_CS_HIGH
> has been enabled for all the CS lines used for a given SPI controller.
>
> However, the SPI framework allows to have on the same controller native
> CS and GPIO CS. The native CS may not support the SPI_CS_HIGH, so they
> should not be setup automatically.
>
> With this patch the setting is done only for the CS that will use a
> GPIO as CS
>
> Fixes: f3186dd87669 ("spi: Optionally use GPIO descriptors for CS GPIOs")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxx>
> ---
> drivers/spi/spi.c | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index 5414a10afd65..1b68acc28c8f 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -1880,15 +1880,7 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
> spi->mode |= SPI_3WIRE;
> if (of_property_read_bool(nc, "spi-lsb-first"))
> spi->mode |= SPI_LSB_FIRST;
> -
> - /*
> - * For descriptors associated with the device, polarity inversion is
> - * handled in the gpiolib, so all chip selects are "active high" in
> - * the logical sense, the gpiolib will invert the line if need be.
> - */
> - if (ctlr->use_gpio_descriptors)
> - spi->mode |= SPI_CS_HIGH;
> - else if (of_property_read_bool(nc, "spi-cs-high"))
> + if (of_property_read_bool(nc, "spi-cs-high"))
> spi->mode |= SPI_CS_HIGH;
>
> /* Device DUAL/QUAD mode */
> @@ -1952,6 +1944,14 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
> }
> spi->chip_select = value;
>
> + /*
> + * For descriptors associated with the device, polarity inversion is
> + * handled in the gpiolib, so all gpio chip selects are "active high"
> + * in the logical sense, the gpiolib will invert the line if need be.
> + */
> + if ((ctlr->use_gpio_descriptors) && ctlr->cs_gpiods[spi->chip_select])
> + spi->mode |= SPI_CS_HIGH;
> +

This patch is causing a boot regression on one of our Tegra boards.
Bisect is pointing to this commit and reverting on top of today's -next
fixes the problem.

This patch is causing the following NULL pointer crash which I assume is
because we have not checked if 'ctlr->cs_gpiods' is valid before
dereferencing ...

[ 2.083593] Unable to handle kernel NULL pointer dereference at virtual address 00000000
[ 2.091800] pgd = (ptrval)
[ 2.094513] [00000000] *pgd=00000000
[ 2.098122] Internal error: Oops: 5 [#1] PREEMPT SMP ARM
[ 2.103436] Modules linked in:
[ 2.106501] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.4.0-rc4-next-20191024-00013-gdda3f5db0962 #402
[ 2.115808] Hardware name: NVIDIA Tegra SoC (Flattened Device Tree)
[ 2.122084] PC is at spi_register_controller+0x870/0xac0
[ 2.127409] LR is at of_find_property+0x44/0x4c
[ 2.131943] pc : [<c0629b98>] lr : [<c078b068>] psr: 20000013
[ 2.138210] sp : ee8cdda8 ip : 00000000 fp : 00000000
[ 2.143436] r10: eefe88e8 r9 : 00000001 r8 : eefe8898
[ 2.148662] r7 : ee2dac00 r6 : c0d2019c r5 : c0d20190 r4 : ee2d8800
[ 2.155190] r3 : 00000000 r2 : 00000000 r1 : ffffffff r0 : 00000001
[ 2.161719] Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
[ 2.168857] Control: 10c5387d Table: 8000406a DAC: 00000051
[ 2.174604] Process swapper/0 (pid: 1, stack limit = 0x(ptrval))
[ 2.180613] Stack: (0xee8cdda8 to 0xee8ce000)
[ 2.184976] dda0: 00000000 00000044 c0629e0c 00000000 c1004e48 c0d202c8
[ 2.193161] ddc0: 00000000 d20df1b4 c0628544 ee2d2040 ee2d8800 eea6c010 eea6c010 40000000
[ 2.201344] dde0: 00000000 00000055 c0f8cd14 c0629e1c ee2d8800 ee2d8bc0 eea6c010 eea6c000
[ 2.209528] de00: 40000000 c062db18 eea6b500 ee2d8bc0 eea6c010 00000000 c10807d4 00000000
[ 2.217710] de20: c10807d4 00000000 00000000 c05b1050 c1110834 eea6c010 c1110838 c05af028
[ 2.225893] de40: eea6c010 c10807d4 c10807d4 c1004e48 00000000 c0f0058c c0f71854 c05af2b8
[ 2.234077] de60: c0f71854 c078be00 c0b91164 eea6c010 00000000 c10807d4 c1004e48 00000000
[ 2.242259] de80: c0f0058c c0f71854 c0f8cd14 c05af568 00000000 c10807d4 eea6c010 c05af5f0
[ 2.250442] dea0: 00000000 c10807d4 c05af570 c05ad39c c0f0058c ee90ea5c eea651b4 d20df1b4
[ 2.258626] dec0: c1077590 c10807d4 ee2d2580 c1077590 00000000 c05ae390 c0d20a60 c10c73a0
[ 2.266809] dee0: ffffe000 c10807d4 c10c73a0 ffffe000 c0f3b368 c05b0144 c1004e48 c10c73a0
[ 2.274992] df00: ffffe000 c010306c 0000011e c01454b4 c0de9d70 c0d32c00 00000000 00000006
[ 2.283175] df20: 00000006 c0cbf1b0 00000000 c1004e48 c0cd2680 c0cbf224 00000000 efffcc21
[ 2.291358] df40: efffcc45 d20df1b4 00000000 c10d4e00 c10d4e00 d20df1b4 c10d4e00 c10d4e00
[ 2.299541] df60: 00000007 c0f71834 0000011e c0f01040 00000006 00000006 00000000 c0f0058c
[ 2.307723] df80: c0aad7c4 00000000 c0aad7c4 00000000 00000000 00000000 00000000 00000000
[ 2.315906] dfa0: 00000000 c0aad7cc 00000000 c01010e8 00000000 00000000 00000000 00000000
[ 2.324088] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 2.332271] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000
[ 2.340463] [<c0629b98>] (spi_register_controller) from [<c0629e1c>] (devm_spi_register_controller+0x34/0x6c)
[ 2.350389] [<c0629e1c>] (devm_spi_register_controller) from [<c062db18>] (tegra_spi_probe+0x33c/0x448)
[ 2.359794] [<c062db18>] (tegra_spi_probe) from [<c05b1050>] (platform_drv_probe+0x48/0x98)
[ 2.368155] [<c05b1050>] (platform_drv_probe) from [<c05af028>] (really_probe+0x234/0x34c)
[ 2.376427] [<c05af028>] (really_probe) from [<c05af2b8>] (driver_probe_device+0x60/0x168)
[ 2.384699] [<c05af2b8>] (driver_probe_device) from [<c05af568>] (device_driver_attach+0x58/0x60)
[ 2.393578] [<c05af568>] (device_driver_attach) from [<c05af5f0>] (__driver_attach+0x80/0xbc)
[ 2.402108] [<c05af5f0>] (__driver_attach) from [<c05ad39c>] (bus_for_each_dev+0x74/0xb4)
[ 2.410292] [<c05ad39c>] (bus_for_each_dev) from [<c05ae390>] (bus_add_driver+0x164/0x1e8)
[ 2.418563] [<c05ae390>] (bus_add_driver) from [<c05b0144>] (driver_register+0x7c/0x114)
[ 2.426663] [<c05b0144>] (driver_register) from [<c010306c>] (do_one_initcall+0x54/0x2a8)
[ 2.434851] [<c010306c>] (do_one_initcall) from [<c0f01040>] (kernel_init_freeable+0x14c/0x1e8)
[ 2.443560] [<c0f01040>] (kernel_init_freeable) from [<c0aad7cc>] (kernel_init+0x8/0x10c)
[ 2.451747] [<c0aad7cc>] (kernel_init) from [<c01010e8>] (ret_from_fork+0x14/0x2c)
[ 2.459318] Exception stack(0xee8cdfb0 to 0xee8cdff8)
[ 2.464374] dfa0: 00000000 00000000 00000000 00000000
[ 2.472557] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 2.480740] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000
[ 2.487362] Code: e3520000 0a000006 e59422f8 e6ef3073 (e7923103)
[ 2.493510] ---[ end trace c189900877242550 ]---

Cheers
Jon

--
nvpublic