[PATCH 1/3] firmware: exynos-acpm: fix reading longer results

[André Draszik]

ACPM commands that return more than 8 bytes currently don't work
correctly, as this driver ignores any such returned bytes.

This is evident in at least acpm_pmic_bulk_read(), where up to 8
registers can be read back and those 8 register values are placed
starting at &xfer->rxd[8].

The reason is that xfter->rxlen is initialized with the size of a
pointer (8 bytes), rather than the size of the byte array that pointer
points to (16 bytes)

Update the code such that we set the number of bytes expected to be the
size of the rx buffer.

Note1: While different commands have different lengths rx buffers, we
have to specify the same length for all rx buffers since acpm_get_rx()
assumes they're all the same length.

Note2: The different commands also have different lengths tx buffers,
but before switching the code to use the minimum possible length, some
more testing would have to be done to ensure this works correctly in
all situations. It seems wiser to just apply this fix here without
additional logic changes for now.

Fixes: a88927b534ba ("firmware: add Exynos ACPM protocol driver")
Signed-off-by: André Draszik <andre.draszik@xxxxxxxxxx>

---
issue is in linux-next only afaics at this stage, as driver is not
merged into Linus' tree yet
---
 drivers/firmware/samsung/exynos-acpm-pmic.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/firmware/samsung/exynos-acpm-pmic.c b/drivers/firmware/samsung/exynos-acpm-pmic.c
index 85e90d236da21ed76f7adba59caec165138ad313..39b33a356ebd240506b6390163229a70a2d1fe68 100644
--- a/drivers/firmware/samsung/exynos-acpm-pmic.c
+++ b/drivers/firmware/samsung/exynos-acpm-pmic.c
@@ -43,13 +43,13 @@ static inline u32 acpm_pmic_get_bulk(u32 data, unsigned int i)
 	return (data >> (ACPM_PMIC_BULK_SHIFT * i)) & ACPM_PMIC_BULK_MASK;
 }
 
-static void acpm_pmic_set_xfer(struct acpm_xfer *xfer, u32 *cmd,
+static void acpm_pmic_set_xfer(struct acpm_xfer *xfer, u32 *cmd, size_t cmdlen,
 			       unsigned int acpm_chan_id)
 {
 	xfer->txd = cmd;
 	xfer->rxd = cmd;
-	xfer->txlen = sizeof(cmd);
-	xfer->rxlen = sizeof(cmd);
+	xfer->txlen = cmdlen;
+	xfer->rxlen = cmdlen;
 	xfer->acpm_chan_id = acpm_chan_id;
 }
 
@@ -71,7 +71,7 @@ int acpm_pmic_read_reg(const struct acpm_handle *handle,
 	int ret;
 
 	acpm_pmic_init_read_cmd(cmd, type, reg, chan);
-	acpm_pmic_set_xfer(&xfer, cmd, acpm_chan_id);
+	acpm_pmic_set_xfer(&xfer, cmd, sizeof(cmd), acpm_chan_id);
 
 	ret = acpm_do_xfer(handle, &xfer);
 	if (ret)
@@ -104,7 +104,7 @@ int acpm_pmic_bulk_read(const struct acpm_handle *handle,
 		return -EINVAL;
 
 	acpm_pmic_init_bulk_read_cmd(cmd, type, reg, chan, count);
-	acpm_pmic_set_xfer(&xfer, cmd, acpm_chan_id);
+	acpm_pmic_set_xfer(&xfer, cmd, sizeof(cmd), acpm_chan_id);
 
 	ret = acpm_do_xfer(handle, &xfer);
 	if (ret)
@@ -144,7 +144,7 @@ int acpm_pmic_write_reg(const struct acpm_handle *handle,
 	int ret;
 
 	acpm_pmic_init_write_cmd(cmd, type, reg, chan, value);
-	acpm_pmic_set_xfer(&xfer, cmd, acpm_chan_id);
+	acpm_pmic_set_xfer(&xfer, cmd, sizeof(cmd), acpm_chan_id);
 
 	ret = acpm_do_xfer(handle, &xfer);
 	if (ret)
@@ -184,7 +184,7 @@ int acpm_pmic_bulk_write(const struct acpm_handle *handle,
 		return -EINVAL;
 
 	acpm_pmic_init_bulk_write_cmd(cmd, type, reg, chan, count, buf);
-	acpm_pmic_set_xfer(&xfer, cmd, acpm_chan_id);
+	acpm_pmic_set_xfer(&xfer, cmd, sizeof(cmd), acpm_chan_id);
 
 	ret = acpm_do_xfer(handle, &xfer);
 	if (ret)
@@ -214,7 +214,7 @@ int acpm_pmic_update_reg(const struct acpm_handle *handle,
 	int ret;
 
 	acpm_pmic_init_update_cmd(cmd, type, reg, chan, value, mask);
-	acpm_pmic_set_xfer(&xfer, cmd, acpm_chan_id);
+	acpm_pmic_set_xfer(&xfer, cmd, sizeof(cmd), acpm_chan_id);
 
 	ret = acpm_do_xfer(handle, &xfer);
 	if (ret)

-- 
2.49.0.rc1.451.g8f38331e32-goog