Re: [PATCH] tinydrm/mipi-dbi: Use dma-safe buffers for all SPI transfers

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@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@linux.intel.com Signed-off-by: Noralf Trønnes noralf@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