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Subject[PATCH v2 05/47] staging: mmal-vchiq: Always return the param size from param_get
From: Dave Stevenson <>

mmal-vchiq is a reimplementation of the userland library for MMAL.
When getting a parameter, the client provides the storage and
the size of the storage. The VPU then returns the size of the
parameter that it wished to return, and as much as possible of
that parameter is returned to the client.

The implementation previously only returned the size provided
by the VPU should it exceed the buffer size. So for parameters
such as the supported encodings list the client had no idea
how much of the provided storage had been populated.

Signed-off-by: Dave Stevenson <>
Signed-off-by: Jacopo Mondi <>
Signed-off-by: Nicolas Saenz Julienne <>
drivers/staging/vc04_services/vchiq-mmal/mmal-vchiq.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/vc04_services/vchiq-mmal/mmal-vchiq.c b/drivers/staging/vc04_services/vchiq-mmal/mmal-vchiq.c
index 3bc04f2ea53a..efdf30b9edf9 100644
--- a/drivers/staging/vc04_services/vchiq-mmal/mmal-vchiq.c
+++ b/drivers/staging/vc04_services/vchiq-mmal/mmal-vchiq.c
@@ -1282,11 +1282,12 @@ static int port_parameter_get(struct vchiq_mmal_instance *instance,
memcpy(value, &rmsg->u.port_parameter_get_reply.value,
- *value_size = rmsg->u.port_parameter_get_reply.size;
} else {
memcpy(value, &rmsg->u.port_parameter_get_reply.value,
+ /* Always report the size of the returned parameter to the caller */
+ *value_size = rmsg->u.port_parameter_get_reply.size;

pr_debug("%s:result:%d component:0x%x port:%d parameter:%d\n", __func__,
ret, port->component->handle, port->handle, parameter_id);
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