[PATCH 0/2] drm/mipi-dbi: Allow using same the D/C GPIO for multiple displays

[PATCH 0/2] drm/mipi-dbi: Allow using same the D/C GPIO for multiple displays

[Otto Pflüger]

When multiple displays are connected to the same SPI bus, the data/command
switch is sometimes considered part of the bus and is shared among the
displays.

This series adds the GPIO_FLAGS_BIT_NONEXCLUSIVE flag for this GPIO and
SPI bus locking to the panel-mipi-dbi/drm_mipi_dbi drivers to support this
hardware setup.

Otto Pflüger (2):
  drm/mipi-dbi: Lock SPI bus before setting D/C GPIO
  drm/tiny: panel-mipi-dbi: Allow sharing the D/C GPIO

 drivers/gpu/drm/drm_mipi_dbi.c        | 22 +++++++++++++++++-----
 drivers/gpu/drm/tiny/panel-mipi-dbi.c |  3 ++-
 include/drm/drm_mipi_dbi.h            |  2 +-
 3 files changed, 20 insertions(+), 7 deletions(-)

-- 
2.39.1

[PATCH 1/2] drm/mipi-dbi: Lock SPI bus before setting D/C GPIO

[Otto Pflüger]

Multiple displays may be connected to the same bus and share a D/C GPIO,
so the display driver needs exclusive access to the bus to ensure that
it can control the D/C GPIO safely.

Signed-off-by: Otto Pflüger <otto.pflueger@abscue.de>
---
 drivers/gpu/drm/drm_mipi_dbi.c | 22 +++++++++++++++++-----
 include/drm/drm_mipi_dbi.h     |  2 +-
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/drm_mipi_dbi.c b/drivers/gpu/drm/drm_mipi_dbi.c
index c871d9f096b8..c205b7594571 100644
--- a/drivers/gpu/drm/drm_mipi_dbi.c
+++ b/drivers/gpu/drm/drm_mipi_dbi.c
@@ -1140,10 +1140,13 @@ static int mipi_dbi_typec3_command_read(struct mipi_dbi *dbi, u8 *cmd,
 		return -ENOMEM;
 
 	tr[1].rx_buf = buf;
+
+	spi_bus_lock(spi->controller);
 	gpiod_set_value_cansleep(dbi->dc, 0);
 
 	spi_message_init_with_transfers(&m, tr, ARRAY_SIZE(tr));
-	ret = spi_sync(spi, &m);
+	ret = spi_sync_locked(spi, &m);
+	spi_bus_unlock(spi->controller);
 	if (ret)
 		goto err_free;
 
@@ -1177,19 +1180,24 @@ static int mipi_dbi_typec3_command(struct mipi_dbi *dbi, u8 *cmd,
 
 	MIPI_DBI_DEBUG_COMMAND(*cmd, par, num);
 
+	spi_bus_lock(spi->controller);
 	gpiod_set_value_cansleep(dbi->dc, 0);
 	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, 1);
-	ret = mipi_dbi_spi_transfer(spi, speed_hz, 8, cmd, 1);
+	ret = mipi_dbi_spi_transfer(spi, speed_hz, 8, cmd, 1, true);
+	spi_bus_unlock(spi->controller);
 	if (ret || !num)
 		return ret;
 
 	if (*cmd == MIPI_DCS_WRITE_MEMORY_START && !dbi->swap_bytes)
 		bpw = 16;
 
+	spi_bus_lock(spi->controller);
 	gpiod_set_value_cansleep(dbi->dc, 1);
 	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, num);
 
-	return mipi_dbi_spi_transfer(spi, speed_hz, bpw, par, num);
+	ret = mipi_dbi_spi_transfer(spi, speed_hz, bpw, par, num, true);
+	spi_bus_unlock(spi->controller);
+	return ret;
 }
 
 /**
@@ -1269,6 +1277,7 @@ EXPORT_SYMBOL(mipi_dbi_spi_init);
  * @bpw: Bits per word
  * @buf: Buffer to transfer
  * @len: Buffer length
+ * @is_locked: Is the SPI bus locked?
  *
  * This SPI transfer helper breaks up the transfer of @buf into chunks which
  * the SPI controller driver can handle.
@@ -1277,7 +1286,7 @@ EXPORT_SYMBOL(mipi_dbi_spi_init);
  * Zero on success, negative error code on failure.
  */
 int mipi_dbi_spi_transfer(struct spi_device *spi, u32 speed_hz,
-			  u8 bpw, const void *buf, size_t len)
+			  u8 bpw, const void *buf, size_t len, bool is_locked)
 {
 	size_t max_chunk = spi_max_transfer_size(spi);
 	struct spi_transfer tr = {
@@ -1305,7 +1314,10 @@ int mipi_dbi_spi_transfer(struct spi_device *spi, u32 speed_hz,
 		buf += chunk;
 		len -= chunk;
 
-		ret = spi_sync(spi, &m);
+		if (is_locked)
+			ret = spi_sync_locked(spi, &m);
+		else
+			ret = spi_sync(spi, &m);
 		if (ret)
 			return ret;
 	}
diff --git a/include/drm/drm_mipi_dbi.h b/include/drm/drm_mipi_dbi.h
index 816f196b3d4c..da632288aff9 100644
--- a/include/drm/drm_mipi_dbi.h
+++ b/include/drm/drm_mipi_dbi.h
@@ -185,7 +185,7 @@ int mipi_dbi_poweron_conditional_reset(struct mipi_dbi_dev *dbidev);
 
 u32 mipi_dbi_spi_cmd_max_speed(struct spi_device *spi, size_t len);
 int mipi_dbi_spi_transfer(struct spi_device *spi, u32 speed_hz,
-			  u8 bpw, const void *buf, size_t len);
+			  u8 bpw, const void *buf, size_t len, bool is_locked);
 
 int mipi_dbi_command_read(struct mipi_dbi *dbi, u8 cmd, u8 *val);
 int mipi_dbi_command_buf(struct mipi_dbi *dbi, u8 cmd, u8 *data, size_t len);
-- 
2.39.1

[PATCH 2/2] drm/tiny: panel-mipi-dbi: Allow sharing the D/C GPIO

[Otto Pflüger]

Displays that are connected to the same SPI bus may share the D/C GPIO.
Use GPIOD_FLAGS_BIT_NONEXCLUSIVE to allow access to the same GPIO for
multiple panel-mipi-dbi instances. Exclusive access to the GPIO during
transfers is ensured by the locking in drm_mipi_dbi.c.

Signed-off-by: Otto Pflüger <otto.pflueger@abscue.de>
---
 drivers/gpu/drm/tiny/panel-mipi-dbi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tiny/panel-mipi-dbi.c b/drivers/gpu/drm/tiny/panel-mipi-dbi.c
index eb9f13f18a02..e616e3890043 100644
--- a/drivers/gpu/drm/tiny/panel-mipi-dbi.c
+++ b/drivers/gpu/drm/tiny/panel-mipi-dbi.c
@@ -307,7 +307,8 @@ static int panel_mipi_dbi_spi_probe(struct spi_device *spi)
 	if (IS_ERR(dbi->reset))
 		return dev_err_probe(dev, PTR_ERR(dbi->reset), "Failed to get GPIO 'reset'\n");
 
-	dc = devm_gpiod_get_optional(dev, "dc", GPIOD_OUT_LOW);
+	dc = devm_gpiod_get_optional(dev, "dc",
+				     GPIOD_OUT_LOW | GPIOD_FLAGS_BIT_NONEXCLUSIVE);
 	if (IS_ERR(dc))
 		return dev_err_probe(dev, PTR_ERR(dc), "Failed to get GPIO 'dc'\n");
 
-- 
2.39.1

Re: [PATCH 1/2] drm/mipi-dbi: Lock SPI bus before setting D/C GPIO

[kernel test robot]

Hi Otto,

kernel test robot noticed the following build errors:

[auto build test ERROR on drm-misc/drm-misc-next]
[also build test ERROR on drm/drm-next drm-exynos/exynos-drm-next drm-intel/for-linux-next drm-intel/for-linux-next-fixes drm-tip/drm-tip linus/master v6.5-rc2 next-20230719]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Otto-Pfl-ger/drm-mipi-dbi-Lock-SPI-bus-before-setting-D-C-GPIO/20230719-180941
base:   git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
patch link:    https://lore.kernel.org/r/20230719095343.88359-2-otto.pflueger%40abscue.de
patch subject: [PATCH 1/2] drm/mipi-dbi: Lock SPI bus before setting D/C GPIO
config: arc-randconfig-r022-20230718 (https://download.01.org/0day-ci/archive/20230719/202307192201.7i1HPQEe-lkp@intel.com/config)
compiler: arceb-elf-gcc (GCC) 12.3.0
reproduce: (https://download.01.org/0day-ci/archive/20230719/202307192201.7i1HPQEe-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202307192201.7i1HPQEe-lkp@intel.com/

All errors (new ones prefixed by >>):

   drivers/gpu/drm/tiny/ili9225.c: In function 'ili9225_dbi_command':
>> drivers/gpu/drm/tiny/ili9225.c:321:15: error: too few arguments to function 'mipi_dbi_spi_transfer'
     321 |         ret = mipi_dbi_spi_transfer(spi, speed_hz, 8, cmd, 1);
         |               ^~~~~~~~~~~~~~~~~~~~~
   In file included from drivers/gpu/drm/tiny/ili9225.c:30:
   include/drm/drm_mipi_dbi.h:187:5: note: declared here
     187 | int mipi_dbi_spi_transfer(struct spi_device *spi, u32 speed_hz,
         |     ^~~~~~~~~~~~~~~~~~~~~
   drivers/gpu/drm/tiny/ili9225.c:331:16: error: too few arguments to function 'mipi_dbi_spi_transfer'
     331 |         return mipi_dbi_spi_transfer(spi, speed_hz, bpw, par, num);
         |                ^~~~~~~~~~~~~~~~~~~~~
   include/drm/drm_mipi_dbi.h:187:5: note: declared here
     187 | int mipi_dbi_spi_transfer(struct spi_device *spi, u32 speed_hz,
         |     ^~~~~~~~~~~~~~~~~~~~~
   drivers/gpu/drm/tiny/ili9225.c:332:1: error: control reaches end of non-void function [-Werror=return-type]
     332 | }
         | ^
   cc1: some warnings being treated as errors


vim +/mipi_dbi_spi_transfer +321 drivers/gpu/drm/tiny/ili9225.c

b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  310  
36b5057216236a drivers/gpu/drm/tinydrm/ili9225.c Noralf Trønnes 2019-07-22  311  static int ili9225_dbi_command(struct mipi_dbi *dbi, u8 *cmd, u8 *par,
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  312  			       size_t num)
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  313  {
36b5057216236a drivers/gpu/drm/tinydrm/ili9225.c Noralf Trønnes 2019-07-22  314  	struct spi_device *spi = dbi->spi;
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  315  	unsigned int bpw = 8;
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  316  	u32 speed_hz;
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  317  	int ret;
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  318  
36b5057216236a drivers/gpu/drm/tinydrm/ili9225.c Noralf Trønnes 2019-07-22  319  	gpiod_set_value_cansleep(dbi->dc, 0);
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  320  	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, 1);
d23d4d4dac0119 drivers/gpu/drm/tinydrm/ili9225.c Noralf Trønnes 2019-07-19 @321  	ret = mipi_dbi_spi_transfer(spi, speed_hz, 8, cmd, 1);
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  322  	if (ret || !num)
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  323  		return ret;
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  324  
36b5057216236a drivers/gpu/drm/tinydrm/ili9225.c Noralf Trønnes 2019-07-22  325  	if (*cmd == ILI9225_WRITE_DATA_TO_GRAM && !dbi->swap_bytes)
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  326  		bpw = 16;
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  327  
36b5057216236a drivers/gpu/drm/tinydrm/ili9225.c Noralf Trønnes 2019-07-22  328  	gpiod_set_value_cansleep(dbi->dc, 1);
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  329  	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, num);
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  330  
d23d4d4dac0119 drivers/gpu/drm/tinydrm/ili9225.c Noralf Trønnes 2019-07-19  331  	return mipi_dbi_spi_transfer(spi, speed_hz, bpw, par, num);
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  332  }
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  333  

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Re: [PATCH 1/2] drm/mipi-dbi: Lock SPI bus before setting D/C GPIO

[kernel test robot]

Hi Otto,

kernel test robot noticed the following build errors:

[auto build test ERROR on drm-misc/drm-misc-next]
[also build test ERROR on drm/drm-next drm-exynos/exynos-drm-next drm-intel/for-linux-next drm-intel/for-linux-next-fixes drm-tip/drm-tip linus/master v6.5-rc2 next-20230719]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Otto-Pfl-ger/drm-mipi-dbi-Lock-SPI-bus-before-setting-D-C-GPIO/20230719-180941
base:   git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
patch link:    https://lore.kernel.org/r/20230719095343.88359-2-otto.pflueger%40abscue.de
patch subject: [PATCH 1/2] drm/mipi-dbi: Lock SPI bus before setting D/C GPIO
config: riscv-randconfig-r042-20230720 (https://download.01.org/0day-ci/archive/20230720/202307200456.jGqv0OSC-lkp@intel.com/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a)
reproduce: (https://download.01.org/0day-ci/archive/20230720/202307200456.jGqv0OSC-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202307200456.jGqv0OSC-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/gpu/drm/tiny/ili9225.c:321:54: error: too few arguments to function call, expected 6, have 5
     321 |         ret = mipi_dbi_spi_transfer(spi, speed_hz, 8, cmd, 1);
         |               ~~~~~~~~~~~~~~~~~~~~~                         ^
   include/drm/drm_mipi_dbi.h:187:5: note: 'mipi_dbi_spi_transfer' declared here
     187 | int mipi_dbi_spi_transfer(struct spi_device *spi, u32 speed_hz,
         |     ^
   drivers/gpu/drm/tiny/ili9225.c:331:59: error: too few arguments to function call, expected 6, have 5
     331 |         return mipi_dbi_spi_transfer(spi, speed_hz, bpw, par, num);
         |                ~~~~~~~~~~~~~~~~~~~~~                             ^
   include/drm/drm_mipi_dbi.h:187:5: note: 'mipi_dbi_spi_transfer' declared here
     187 | int mipi_dbi_spi_transfer(struct spi_device *spi, u32 speed_hz,
         |     ^
   2 errors generated.


vim +321 drivers/gpu/drm/tiny/ili9225.c

b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  310  
36b5057216236a drivers/gpu/drm/tinydrm/ili9225.c Noralf Trønnes 2019-07-22  311  static int ili9225_dbi_command(struct mipi_dbi *dbi, u8 *cmd, u8 *par,
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  312  			       size_t num)
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  313  {
36b5057216236a drivers/gpu/drm/tinydrm/ili9225.c Noralf Trønnes 2019-07-22  314  	struct spi_device *spi = dbi->spi;
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  315  	unsigned int bpw = 8;
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  316  	u32 speed_hz;
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  317  	int ret;
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  318  
36b5057216236a drivers/gpu/drm/tinydrm/ili9225.c Noralf Trønnes 2019-07-22  319  	gpiod_set_value_cansleep(dbi->dc, 0);
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  320  	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, 1);
d23d4d4dac0119 drivers/gpu/drm/tinydrm/ili9225.c Noralf Trønnes 2019-07-19 @321  	ret = mipi_dbi_spi_transfer(spi, speed_hz, 8, cmd, 1);
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  322  	if (ret || !num)
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  323  		return ret;
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  324  
36b5057216236a drivers/gpu/drm/tinydrm/ili9225.c Noralf Trønnes 2019-07-22  325  	if (*cmd == ILI9225_WRITE_DATA_TO_GRAM && !dbi->swap_bytes)
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  326  		bpw = 16;
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  327  
36b5057216236a drivers/gpu/drm/tinydrm/ili9225.c Noralf Trønnes 2019-07-22  328  	gpiod_set_value_cansleep(dbi->dc, 1);
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  329  	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, num);
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  330  
d23d4d4dac0119 drivers/gpu/drm/tinydrm/ili9225.c Noralf Trønnes 2019-07-19  331  	return mipi_dbi_spi_transfer(spi, speed_hz, bpw, par, num);
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  332  }
b57e8b7661e046 drivers/gpu/drm/tinydrm/ili9225.c David Lechner  2017-11-19  333  

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