ipc_service: static_vrings: fix num_desc return value

rghaddab · carlescufi · commit 5eaace1c0102 · 2023-08-30T14:44:51.000+02:00
currently when no enough memory is found a (1 &lt;&lt; (-1)) value is returned
instead of 0.
Fix this by returning 0 and simplify log2 computation

Signed-off-by: Riadh Ghaddab &lt;rghaddab@baylibre.com&gt;
diff --git a/subsys/ipc/ipc_service/backends/ipc_rpmsg_static_vrings.h b/subsys/ipc/ipc_service/backends/ipc_rpmsg_static_vrings.h
@@ -163,5 +163,6 @@ static inline unsigned int optimal_num_desc(size_t mem_size, unsigned int buf_si
 		num_desc++;
 	}
 
-	return (1 << (find_msb_set(--num_desc) - 1));
+	/* if num_desc == 1 there is not enough memory */
+	return (--num_desc == 0) ? 0 : (1 << LOG2(num_desc));
 }

Original file line number	Diff line number	Diff line change
`@@ -163,5 +163,6 @@ static inline unsigned int optimal_num_desc(size_t mem_size, unsigned int buf_si`
`163`	`163`	`num_desc++;`
`164`	`164`	`}`
`165`	`165`
`166`		`- return (1 << (find_msb_set(--num_desc) - 1));`
	`166`	`+ /* if num_desc == 1 there is not enough memory */`
	`167`	`+ return (--num_desc == 0) ? 0 : (1 << LOG2(num_desc));`
`167`	`168`	`}`