[PATCH v2 1/3] soundwire: bus: Remove now outdated comments on no_pm IO

[PATCH v2 1/3] soundwire: bus: Remove now outdated comments on no_pm IO

[Charles Keepax]

Things have moved more towards end drivers using the no_pm versions of
the IO functions. See commits:

commit 167790abb90f ("soundwire: export sdw_write/read_no_pm functions")
commit 62dc9f3f2fd0 ("soundwire: bus: export sdw_nwrite_no_pm and
                      sdw_nread_no_pm functions")

As such this comment is now misleading, so remove it.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
---

No change since v1.

 drivers/soundwire/bus.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index b6aca59c31300..3c67266f94834 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -384,9 +384,6 @@ int sdw_fill_msg(struct sdw_msg *msg, struct sdw_slave *slave,
 
 /*
  * Read/Write IO functions.
- * no_pm versions can only be called by the bus, e.g. while enumerating or
- * handling suspend-resume sequences.
- * all clients need to use the pm versions
  */
 
 int sdw_nread_no_pm(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
-- 
2.30.2

[PATCH v2 2/3] soundwire: bus: Update kernel doc for no_pm functions

[Charles Keepax]

The kernel doc should really have been updated when the no_pm versions
of the sdw_write/read functions were exported in commits:

commit 167790abb90f ("soundwire: export sdw_write/read_no_pm functions")
commit 62dc9f3f2fd0 ("soundwire: bus: export sdw_nwrite_no_pm and
                      sdw_nread_no_pm functions")

Add the missing kernel doc.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
---

New since v1.

 drivers/soundwire/bus.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 3c67266f94834..f1ffb8e0839dd 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -386,6 +386,13 @@ int sdw_fill_msg(struct sdw_msg *msg, struct sdw_slave *slave,
  * Read/Write IO functions.
  */
 
+/**
+ * sdw_nread_no_pm() - Read "n" contiguous SDW Slave registers with no PM
+ * @slave: SDW Slave
+ * @addr: Register address
+ * @count: length
+ * @val: Buffer for values to be read
+ */
 int sdw_nread_no_pm(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
 {
 	struct sdw_msg msg;
@@ -403,6 +410,13 @@ int sdw_nread_no_pm(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
 }
 EXPORT_SYMBOL(sdw_nread_no_pm);
 
+/**
+ * sdw_nwrite_no_pm() - Write "n" contiguous SDW Slave registers with no PM
+ * @slave: SDW Slave
+ * @addr: Register address
+ * @count: length
+ * @val: Buffer for values to be written
+ */
 int sdw_nwrite_no_pm(struct sdw_slave *slave, u32 addr, size_t count, const u8 *val)
 {
 	struct sdw_msg msg;
@@ -420,6 +434,12 @@ int sdw_nwrite_no_pm(struct sdw_slave *slave, u32 addr, size_t count, const u8 *
 }
 EXPORT_SYMBOL(sdw_nwrite_no_pm);
 
+/**
+ * sdw_write_no_pm() - Write a SDW Slave register with no PM
+ * @slave: SDW Slave
+ * @addr: Register address
+ * @value: Register value
+ */
 int sdw_write_no_pm(struct sdw_slave *slave, u32 addr, u8 value)
 {
 	return sdw_nwrite_no_pm(slave, addr, 1, &value);
@@ -492,6 +512,11 @@ int sdw_bwrite_no_pm_unlocked(struct sdw_bus *bus, u16 dev_num, u32 addr, u8 val
 }
 EXPORT_SYMBOL(sdw_bwrite_no_pm_unlocked);
 
+/**
+ * sdw_read_no_pm() - Read a SDW Slave register with no PM
+ * @slave: SDW Slave
+ * @addr: Register address
+ */
 int sdw_read_no_pm(struct sdw_slave *slave, u32 addr)
 {
 	u8 buf;
@@ -538,6 +563,9 @@ EXPORT_SYMBOL(sdw_update);
  * @addr: Register address
  * @count: length
  * @val: Buffer for values to be read
+ *
+ * This version of the function will take a PM reference to the slave
+ * device.
  */
 int sdw_nread(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
 {
@@ -562,6 +590,9 @@ EXPORT_SYMBOL(sdw_nread);
  * @addr: Register address
  * @count: length
  * @val: Buffer for values to be written
+ *
+ * This version of the function will take a PM reference to the slave
+ * device.
  */
 int sdw_nwrite(struct sdw_slave *slave, u32 addr, size_t count, const u8 *val)
 {
@@ -584,6 +615,9 @@ EXPORT_SYMBOL(sdw_nwrite);
  * sdw_read() - Read a SDW Slave register
  * @slave: SDW Slave
  * @addr: Register address
+ *
+ * This version of the function will take a PM reference to the slave
+ * device.
  */
 int sdw_read(struct sdw_slave *slave, u32 addr)
 {
@@ -603,6 +637,9 @@ EXPORT_SYMBOL(sdw_read);
  * @slave: SDW Slave
  * @addr: Register address
  * @value: Register value
+ *
+ * This version of the function will take a PM reference to the slave
+ * device.
  */
 int sdw_write(struct sdw_slave *slave, u32 addr, u8 value)
 {
-- 
2.30.2

[PATCH v2 3/3] soundwire: bus: Update sdw_nread/nwrite_no_pm to handle page boundaries

[Charles Keepax]

Currently issuing a sdw_nread/nwrite_no_pm across a page boundary
will silently fail to write correctly as nothing updates the page
registers, meaning the same page of the chip will get rewritten
with each successive page of data.

As the sdw_msg structure contains page information it seems
reasonable that a single sdw_msg should always be within one
page. It is also mostly simpler to handle the paging at the
bus level rather than each master having to handle it in their
xfer_msg callback.

As such add handling to the bus code to split up a transfer into
multiple sdw_msg's when they go across page boundaries.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
---

Changes since v1:
 - Switch from min to min_t to avoid the build issues on MIPs/i386
 - Added comments to the kernel doc to say that large transactions will
   be broken up.

Thanks,
Charles

 drivers/soundwire/bus.c | 63 +++++++++++++++++++++++++----------------
 1 file changed, 39 insertions(+), 24 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index f1ffb8e0839dd..e157a39a82ce5 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -386,27 +386,46 @@ int sdw_fill_msg(struct sdw_msg *msg, struct sdw_slave *slave,
  * Read/Write IO functions.
  */
 
+static int sdw_ntransfer_no_pm(struct sdw_slave *slave, u32 addr, u8 flags,
+			       size_t count, u8 *val)
+{
+	struct sdw_msg msg;
+	size_t size;
+	int ret;
+
+	while (count) {
+		// Only handle bytes up to next page boundary
+		size = min_t(size_t, count, (SDW_REGADDR + 1) - (addr & SDW_REGADDR));
+
+		ret = sdw_fill_msg(&msg, slave, addr, size, slave->dev_num, flags, val);
+		if (ret < 0)
+			return ret;
+
+		ret = sdw_transfer(slave->bus, &msg);
+		if (ret < 0 && !slave->is_mockup_device)
+			return ret;
+
+		addr += size;
+		val += size;
+		count -= size;
+	}
+
+	return 0;
+}
+
 /**
  * sdw_nread_no_pm() - Read "n" contiguous SDW Slave registers with no PM
  * @slave: SDW Slave
  * @addr: Register address
  * @count: length
  * @val: Buffer for values to be read
+ *
+ * Note that if the message crosses a page boundary each page will be
+ * transferred under a separate invocation of the msg_lock.
  */
 int sdw_nread_no_pm(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
 {
-	struct sdw_msg msg;
-	int ret;
-
-	ret = sdw_fill_msg(&msg, slave, addr, count,
-			   slave->dev_num, SDW_MSG_FLAG_READ, val);
-	if (ret < 0)
-		return ret;
-
-	ret = sdw_transfer(slave->bus, &msg);
-	if (slave->is_mockup_device)
-		ret = 0;
-	return ret;
+	return sdw_ntransfer_no_pm(slave, addr, SDW_MSG_FLAG_READ, count, val);
 }
 EXPORT_SYMBOL(sdw_nread_no_pm);
 
@@ -416,21 +435,13 @@ EXPORT_SYMBOL(sdw_nread_no_pm);
  * @addr: Register address
  * @count: length
  * @val: Buffer for values to be written
+ *
+ * Note that if the message crosses a page boundary each page will be
+ * transferred under a separate invocation of the msg_lock.
  */
 int sdw_nwrite_no_pm(struct sdw_slave *slave, u32 addr, size_t count, const u8 *val)
 {
-	struct sdw_msg msg;
-	int ret;
-
-	ret = sdw_fill_msg(&msg, slave, addr, count,
-			   slave->dev_num, SDW_MSG_FLAG_WRITE, (u8 *)val);
-	if (ret < 0)
-		return ret;
-
-	ret = sdw_transfer(slave->bus, &msg);
-	if (slave->is_mockup_device)
-		ret = 0;
-	return ret;
+	return sdw_ntransfer_no_pm(slave, addr, SDW_MSG_FLAG_WRITE, count, (u8 *)val);
 }
 EXPORT_SYMBOL(sdw_nwrite_no_pm);
 
@@ -566,6 +577,8 @@ EXPORT_SYMBOL(sdw_update);
  *
  * This version of the function will take a PM reference to the slave
  * device.
+ * Note that if the message crosses a page boundary each page will be
+ * transferred under a separate invocation of the msg_lock.
  */
 int sdw_nread(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
 {
@@ -593,6 +606,8 @@ EXPORT_SYMBOL(sdw_nread);
  *
  * This version of the function will take a PM reference to the slave
  * device.
+ * Note that if the message crosses a page boundary each page will be
+ * transferred under a separate invocation of the msg_lock.
  */
 int sdw_nwrite(struct sdw_slave *slave, u32 addr, size_t count, const u8 *val)
 {
-- 
2.30.2

Re: [PATCH v2 1/3] soundwire: bus: Remove now outdated comments on no_pm IO

[Vinod Koul]

On 22-03-23, 16:49, Charles Keepax wrote:
> Things have moved more towards end drivers using the no_pm versions of
> the IO functions. See commits:
> 
> commit 167790abb90f ("soundwire: export sdw_write/read_no_pm functions")
> commit 62dc9f3f2fd0 ("soundwire: bus: export sdw_nwrite_no_pm and
>                       sdw_nread_no_pm functions")
> 
> As such this comment is now misleading, so remove it.

Applied all, thanks

-- 
~Vinod