[PATCH] tinydrm/mipi-dbi: Use dma-safe buffers for all SPI transfers
Andy Shevchenko
andriy.shevchenko at linux.intel.com
Fri Feb 22 15:58:01 UTC 2019
On Fri, Feb 22, 2019 at 01:43:29PM +0100, Noralf Trønnes wrote:
> Buffers passed to spi_sync() must be dma-safe even for tiny buffers since
> some SPI controllers use DMA for all transfers.
>
> Example splat with CONFIG_DMA_API_DEBUG enabled:
>
> [ 23.750467] DMA-API: dw_dmac_pci 0000:00:15.0: device driver maps memory from stack [probable addr=000000001e49185d]
> [ 23.750529] WARNING: CPU: 1 PID: 1296 at kernel/dma/debug.c:1161 check_for_stack+0xb7/0x190
> [ 23.750533] Modules linked in: mmc_block(+) spi_pxa2xx_platform(+) pwm_lpss_pci pwm_lpss spi_pxa2xx_pci sdhci_pci cqhci intel_mrfld_pwrbtn extcon_intel_mrfld sdhci intel_mrfld_adc led_class mmc_core ili9341 mipi_dbi tinydrm backlight ti_ads7950 industrialio_triggered_buffer kfifo_buf intel_soc_pmic_mrfld hci_uart btbcm
> [ 23.750599] CPU: 1 PID: 1296 Comm: modprobe Not tainted 5.0.0-rc7+ #236
> [ 23.750605] Hardware name: Intel Corporation Merrifield/BODEGA BAY, BIOS 542 2015.01.21:18.19.48
> [ 23.750620] RIP: 0010:check_for_stack+0xb7/0x190
> [ 23.750630] Code: 8b 6d 50 4d 85 ed 75 04 4c 8b 6d 10 48 89 ef e8 2f 8b 44 00 48 89 c6 4a 8d 0c 23 4c 89 ea 48 c7 c7 88 d0 82 b4 e8 40 7c f9 ff <0f> 0b 8b 05 79 00 4b 01 85 c0 74 07 5b 5d 41 5c 41 5d c3 8b 05 54
> [ 23.750637] RSP: 0000:ffff97bbc0292fa0 EFLAGS: 00010286
> [ 23.750646] RAX: 0000000000000000 RBX: ffff97bbc0290000 RCX: 0000000000000006
> [ 23.750652] RDX: 0000000000000007 RSI: 0000000000000002 RDI: ffff94b33e115450
> [ 23.750658] RBP: ffff94b33c8578b0 R08: 0000000000000002 R09: 00000000000201c0
> [ 23.750664] R10: 00000006ecb0ccc6 R11: 0000000000034f38 R12: 000000000000316c
> [ 23.750670] R13: ffff94b33c84b250 R14: ffff94b33dedd5a0 R15: 0000000000000001
> [ 23.750679] FS: 0000000000000000(0000) GS:ffff94b33e100000(0063) knlGS:00000000f7faf690
> [ 23.750686] CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
> [ 23.750691] CR2: 00000000f7f54faf CR3: 000000000722c000 CR4: 00000000001006e0
> [ 23.750696] Call Trace:
> [ 23.750713] debug_dma_map_sg+0x100/0x340
> [ 23.750727] ? dma_direct_map_sg+0x3b/0xb0
> [ 23.750739] spi_map_buf+0x25a/0x300
> [ 23.750751] __spi_pump_messages+0x2a4/0x680
> [ 23.750762] __spi_sync+0x1dd/0x1f0
> [ 23.750773] spi_sync+0x26/0x40
> [ 23.750790] mipi_dbi_typec3_command_read+0x14d/0x240 [mipi_dbi]
> [ 23.750802] ? spi_finalize_current_transfer+0x10/0x10
> [ 23.750821] mipi_dbi_typec3_command+0x1bc/0x1d0 [mipi_dbi]
>
After few runs I don't see the warning anymore. So,
Tested-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
Though I would like to give few more days to monitor the state.
(I believe it's fixed)
> Reported-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
> Signed-off-by: Noralf Trønnes <noralf at tronnes.org>
> ---
> drivers/gpu/drm/tinydrm/ili9225.c | 6 ++--
> drivers/gpu/drm/tinydrm/mipi-dbi.c | 58 +++++++++++++++++++++---------
> include/drm/tinydrm/mipi-dbi.h | 5 +--
> 3 files changed, 48 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/gpu/drm/tinydrm/ili9225.c b/drivers/gpu/drm/tinydrm/ili9225.c
> index 3f59cfbd31ba..a87078667e04 100644
> --- a/drivers/gpu/drm/tinydrm/ili9225.c
> +++ b/drivers/gpu/drm/tinydrm/ili9225.c
> @@ -299,7 +299,7 @@ static void ili9225_pipe_disable(struct drm_simple_display_pipe *pipe)
> mipi->enabled = false;
> }
>
> -static int ili9225_dbi_command(struct mipi_dbi *mipi, u8 cmd, u8 *par,
> +static int ili9225_dbi_command(struct mipi_dbi *mipi, u8 *cmd, u8 *par,
> size_t num)
> {
> struct spi_device *spi = mipi->spi;
> @@ -309,11 +309,11 @@ static int ili9225_dbi_command(struct mipi_dbi *mipi, u8 cmd, u8 *par,
>
> gpiod_set_value_cansleep(mipi->dc, 0);
> speed_hz = mipi_dbi_spi_cmd_max_speed(spi, 1);
> - ret = tinydrm_spi_transfer(spi, speed_hz, NULL, 8, &cmd, 1);
> + ret = tinydrm_spi_transfer(spi, speed_hz, NULL, 8, cmd, 1);
> if (ret || !num)
> return ret;
>
> - if (cmd == ILI9225_WRITE_DATA_TO_GRAM && !mipi->swap_bytes)
> + if (*cmd == ILI9225_WRITE_DATA_TO_GRAM && !mipi->swap_bytes)
> bpw = 16;
>
> gpiod_set_value_cansleep(mipi->dc, 1);
> diff --git a/drivers/gpu/drm/tinydrm/mipi-dbi.c b/drivers/gpu/drm/tinydrm/mipi-dbi.c
> index 246e708a9ff7..4a4cd7e72938 100644
> --- a/drivers/gpu/drm/tinydrm/mipi-dbi.c
> +++ b/drivers/gpu/drm/tinydrm/mipi-dbi.c
> @@ -153,16 +153,42 @@ EXPORT_SYMBOL(mipi_dbi_command_read);
> */
> int mipi_dbi_command_buf(struct mipi_dbi *mipi, u8 cmd, u8 *data, size_t len)
> {
> + u8 *cmdbuf;
> int ret;
>
> + /* SPI requires dma-safe buffers */
> + cmdbuf = kmemdup(&cmd, 1, GFP_KERNEL);
> + if (!cmdbuf)
> + return -ENOMEM;
> +
> mutex_lock(&mipi->cmdlock);
> - ret = mipi->command(mipi, cmd, data, len);
> + ret = mipi->command(mipi, cmdbuf, data, len);
> mutex_unlock(&mipi->cmdlock);
>
> + kfree(cmdbuf);
> +
> return ret;
> }
> EXPORT_SYMBOL(mipi_dbi_command_buf);
>
> +/* This should only be used by mipi_dbi_command() */
> +int mipi_dbi_command_stackbuf(struct mipi_dbi *mipi, u8 cmd, u8 *data, size_t len)
> +{
> + u8 *buf;
> + int ret;
> +
> + buf = kmemdup(data, len, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
> +
> + ret = mipi_dbi_command_buf(mipi, cmd, buf, len);
> +
> + kfree(buf);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(mipi_dbi_command_stackbuf);
> +
> /**
> * mipi_dbi_buf_copy - Copy a framebuffer, transforming it if necessary
> * @dst: The destination buffer
> @@ -772,18 +798,18 @@ static int mipi_dbi_spi1_transfer(struct mipi_dbi *mipi, int dc,
> return 0;
> }
>
> -static int mipi_dbi_typec1_command(struct mipi_dbi *mipi, u8 cmd,
> +static int mipi_dbi_typec1_command(struct mipi_dbi *mipi, u8 *cmd,
> u8 *parameters, size_t num)
> {
> - unsigned int bpw = (cmd == MIPI_DCS_WRITE_MEMORY_START) ? 16 : 8;
> + unsigned int bpw = (*cmd == MIPI_DCS_WRITE_MEMORY_START) ? 16 : 8;
> int ret;
>
> - if (mipi_dbi_command_is_read(mipi, cmd))
> + if (mipi_dbi_command_is_read(mipi, *cmd))
> return -ENOTSUPP;
>
> - MIPI_DBI_DEBUG_COMMAND(cmd, parameters, num);
> + MIPI_DBI_DEBUG_COMMAND(*cmd, parameters, num);
>
> - ret = mipi_dbi_spi1_transfer(mipi, 0, &cmd, 1, 8);
> + ret = mipi_dbi_spi1_transfer(mipi, 0, cmd, 1, 8);
> if (ret || !num)
> return ret;
>
> @@ -792,7 +818,7 @@ static int mipi_dbi_typec1_command(struct mipi_dbi *mipi, u8 cmd,
>
> /* MIPI DBI Type C Option 3 */
>
> -static int mipi_dbi_typec3_command_read(struct mipi_dbi *mipi, u8 cmd,
> +static int mipi_dbi_typec3_command_read(struct mipi_dbi *mipi, u8 *cmd,
> u8 *data, size_t len)
> {
> struct spi_device *spi = mipi->spi;
> @@ -801,7 +827,7 @@ static int mipi_dbi_typec3_command_read(struct mipi_dbi *mipi, u8 cmd,
> struct spi_transfer tr[2] = {
> {
> .speed_hz = speed_hz,
> - .tx_buf = &cmd,
> + .tx_buf = cmd,
> .len = 1,
> }, {
> .speed_hz = speed_hz,
> @@ -819,8 +845,8 @@ static int mipi_dbi_typec3_command_read(struct mipi_dbi *mipi, u8 cmd,
> * Support non-standard 24-bit and 32-bit Nokia read commands which
> * start with a dummy clock, so we need to read an extra byte.
> */
> - if (cmd == MIPI_DCS_GET_DISPLAY_ID ||
> - cmd == MIPI_DCS_GET_DISPLAY_STATUS) {
> + if (*cmd == MIPI_DCS_GET_DISPLAY_ID ||
> + *cmd == MIPI_DCS_GET_DISPLAY_STATUS) {
> if (!(len == 3 || len == 4))
> return -EINVAL;
>
> @@ -850,7 +876,7 @@ static int mipi_dbi_typec3_command_read(struct mipi_dbi *mipi, u8 cmd,
> data[i] = (buf[i] << 1) | !!(buf[i + 1] & BIT(7));
> }
>
> - MIPI_DBI_DEBUG_COMMAND(cmd, data, len);
> + MIPI_DBI_DEBUG_COMMAND(*cmd, data, len);
>
> err_free:
> kfree(buf);
> @@ -858,7 +884,7 @@ static int mipi_dbi_typec3_command_read(struct mipi_dbi *mipi, u8 cmd,
> return ret;
> }
>
> -static int mipi_dbi_typec3_command(struct mipi_dbi *mipi, u8 cmd,
> +static int mipi_dbi_typec3_command(struct mipi_dbi *mipi, u8 *cmd,
> u8 *par, size_t num)
> {
> struct spi_device *spi = mipi->spi;
> @@ -866,18 +892,18 @@ static int mipi_dbi_typec3_command(struct mipi_dbi *mipi, u8 cmd,
> u32 speed_hz;
> int ret;
>
> - if (mipi_dbi_command_is_read(mipi, cmd))
> + if (mipi_dbi_command_is_read(mipi, *cmd))
> return mipi_dbi_typec3_command_read(mipi, cmd, par, num);
>
> - MIPI_DBI_DEBUG_COMMAND(cmd, par, num);
> + MIPI_DBI_DEBUG_COMMAND(*cmd, par, num);
>
> gpiod_set_value_cansleep(mipi->dc, 0);
> speed_hz = mipi_dbi_spi_cmd_max_speed(spi, 1);
> - ret = tinydrm_spi_transfer(spi, speed_hz, NULL, 8, &cmd, 1);
> + ret = tinydrm_spi_transfer(spi, speed_hz, NULL, 8, cmd, 1);
> if (ret || !num)
> return ret;
>
> - if (cmd == MIPI_DCS_WRITE_MEMORY_START && !mipi->swap_bytes)
> + if (*cmd == MIPI_DCS_WRITE_MEMORY_START && !mipi->swap_bytes)
> bpw = 16;
>
> gpiod_set_value_cansleep(mipi->dc, 1);
> diff --git a/include/drm/tinydrm/mipi-dbi.h b/include/drm/tinydrm/mipi-dbi.h
> index ad7e6bedab5f..464a47d1013d 100644
> --- a/include/drm/tinydrm/mipi-dbi.h
> +++ b/include/drm/tinydrm/mipi-dbi.h
> @@ -43,7 +43,7 @@ struct mipi_dbi {
> struct spi_device *spi;
> bool enabled;
> struct mutex cmdlock;
> - int (*command)(struct mipi_dbi *mipi, u8 cmd, u8 *param, size_t num);
> + int (*command)(struct mipi_dbi *mipi, u8 *cmd, u8 *param, size_t num);
> const u8 *read_commands;
> struct gpio_desc *dc;
> u16 *tx_buf;
> @@ -83,6 +83,7 @@ u32 mipi_dbi_spi_cmd_max_speed(struct spi_device *spi, size_t len);
>
> int mipi_dbi_command_read(struct mipi_dbi *mipi, u8 cmd, u8 *val);
> int mipi_dbi_command_buf(struct mipi_dbi *mipi, u8 cmd, u8 *data, size_t len);
> +int mipi_dbi_command_stackbuf(struct mipi_dbi *mipi, u8 cmd, u8 *data, size_t len);
> int mipi_dbi_buf_copy(void *dst, struct drm_framebuffer *fb,
> struct drm_rect *clip, bool swap);
> /**
> @@ -100,7 +101,7 @@ int mipi_dbi_buf_copy(void *dst, struct drm_framebuffer *fb,
> #define mipi_dbi_command(mipi, cmd, seq...) \
> ({ \
> u8 d[] = { seq }; \
> - mipi_dbi_command_buf(mipi, cmd, d, ARRAY_SIZE(d)); \
> + mipi_dbi_command_stackbuf(mipi, cmd, d, ARRAY_SIZE(d)); \
> })
>
> #ifdef CONFIG_DEBUG_FS
> --
> 2.20.1
>
--
With Best Regards,
Andy Shevchenko
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