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authorCarlo Caione <carlo@endlessm.com>2017-03-03 16:17:59 +0100
committerKevin Hilman <khilman@baylibre.com>2017-03-23 12:22:40 -0700
commit7a9bc330df9b8fb3245d50a198b5c6d4d634b06f (patch)
tree2a0eb3dff0c28d6a29acf38baf46f49a9323dabe /drivers/firmware
parent83e007a0c6a3f4bfdf8f3f8d0fc266cda189b3d6 (diff)
downloadlinux-7a9bc330df9b8fb3245d50a198b5c6d4d634b06f.tar.bz2
firmware: meson-sm: Allow 0 as valid return value
Some special SMC calls (i.e. the function used to retrieve the serial number of the Amlogic SoCs) returns 0 in the register 0 also when the data was successfully read instead of using the register to hold the number of bytes returned in the bounce buffer as expected. With the current implementation of the driver this is seen as an error and meson_sm_call_read() returns an error even though the data was correctly read. To deal with this when we have no information about the amount of read data (that is 0 is returned by the SMC call) we return to the caller the requested amount of data and 0 as return value. Signed-off-by: Carlo Caione <carlo@endlessm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Diffstat (limited to 'drivers/firmware')
-rw-r--r--drivers/firmware/meson/meson_sm.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/firmware/meson/meson_sm.c b/drivers/firmware/meson/meson_sm.c
index 5f30a5774e57..ff204421117b 100644
--- a/drivers/firmware/meson/meson_sm.c
+++ b/drivers/firmware/meson/meson_sm.c
@@ -136,11 +136,14 @@ EXPORT_SYMBOL(meson_sm_call);
* @arg4: SMC32 Argument 4
*
* Return: size of read data on success, a negative value on error
+ * When 0 is returned there is no guarantee about the amount of
+ * data read and bsize bytes are copied in buffer.
*/
int meson_sm_call_read(void *buffer, unsigned int bsize, unsigned int cmd_index,
u32 arg0, u32 arg1, u32 arg2, u32 arg3, u32 arg4)
{
u32 size;
+ int ret;
if (!fw.chip)
return -ENOENT;
@@ -154,13 +157,18 @@ int meson_sm_call_read(void *buffer, unsigned int bsize, unsigned int cmd_index,
if (meson_sm_call(cmd_index, &size, arg0, arg1, arg2, arg3, arg4) < 0)
return -EINVAL;
- if (!size || size > bsize)
+ if (size > bsize)
return -EINVAL;
+ ret = size;
+
+ if (!size)
+ size = bsize;
+
if (buffer)
memcpy(buffer, fw.sm_shmem_out_base, size);
- return size;
+ return ret;
}
EXPORT_SYMBOL(meson_sm_call_read);