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tinydrm/mipi-dbi: Use dma-safe buffers for all SPI transfers
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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+ torvalds#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]

Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
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@notro @andy-shev
notro authored and andy-shev committed Apr 29, 2019
1 parent 27ad248 commit d2af3a6
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Showing 3 changed files with 48 additions and 21 deletions.
6 changes: 3 additions & 3 deletions drivers/gpu/drm/tinydrm/ili9225.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -301,7 +301,7 @@ 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;
Expand All @@ -311,11 +311,11 @@ 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);
Expand Down
58 changes: 42 additions & 16 deletions drivers/gpu/drm/tinydrm/mipi-dbi.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -774,18 +800,18 @@ 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;

Expand All @@ -794,7 +820,7 @@ 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;
Expand All @@ -803,7 +829,7 @@ 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,
Expand All @@ -821,8 +847,8 @@ 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;

Expand Down Expand Up @@ -852,34 +878,34 @@ 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);

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;
unsigned int bpw = 8;
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);
Expand Down
5 changes: 3 additions & 2 deletions include/drm/tinydrm/mipi-dbi.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -82,6 +82,7 @@ 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);
/**
Expand All @@ -99,7 +100,7 @@ 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
Expand Down

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