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Subject[PATCH 4.19 247/276] tinydrm/mipi-dbi: Use dma-safe buffers for all SPI transfers
Date
[ Upstream commit a89bfc5d9a0732d84b4de311e27133daa0586316 ]

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]

Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190222124329.23046-1-noralf@tronnes.org
Signed-off-by: Sasha Levin <sashal@kernel.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 455fefe012f59..6044a01069ce2 100644
--- a/drivers/gpu/drm/tinydrm/ili9225.c
+++ b/drivers/gpu/drm/tinydrm/ili9225.c
@@ -278,7 +278,7 @@ 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;
@@ -288,11 +288,11 @@ 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 cb3441e51d5f0..e772a8a9da80e 100644
--- a/drivers/gpu/drm/tinydrm/mipi-dbi.c
+++ b/drivers/gpu/drm/tinydrm/mipi-dbi.c
@@ -144,16 +144,42 @@ 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
@@ -741,18 +767,18 @@ 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;

@@ -761,7 +787,7 @@ 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;
@@ -770,7 +796,7 @@ 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,
@@ -788,8 +814,8 @@ 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;

@@ -819,7 +845,7 @@ 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);
@@ -827,7 +853,7 @@ 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;
@@ -835,18 +861,18 @@ 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 b8ba588619867..bcc98bd447f7a 100644
--- a/include/drm/tinydrm/mipi-dbi.h
+++ b/include/drm/tinydrm/mipi-dbi.h
@@ -42,7 +42,7 @@ 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;
@@ -79,6 +79,7 @@ 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_clip_rect *clip, bool swap);
/**
@@ -96,7 +97,7 @@ 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


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