topology2: intel: deep-buffer: Adjust the buffer_size_min only

There is no benefit on changing the period/buffer size_max as it is set
by default to a reasonably large value already.
What matters is the buffer_size_min: it needs to be larger than the
amount of data that one DMA burst will transfer, which is equal to the
DeepBuffer size. For safety reasons the minimum buffer size has to be
larger than this.

Signed-off-by: Peter Ujfalusi <[email protected]>

tools/topology/topology2/platform/intel/deep-buffer.conf

@@ -33,9 +33,14 @@ Object.PCM.pcm [
 		Object.PCM.pcm_caps.1 {
 			name $DEEP_BUFFER_PCM_NAME
 			formats 'S16_LE,S24_LE,S32_LE'
-			# align with $DEEPBUFFER_FW_DMA_MS
-			period_size_max		65535
-			buffer_size_max		262144
+			# To avoid DMA spinning on a buffer we need bigger
+			# buffer than the host buffer size, let's say twice as
+			# big
+			# (S16_LE, Stereo, 48KHz, DEEPBUFFER_FW_DMA_MS) * 2
+			#
+			# Note: The lower limit for the buffer size is rate
+			#	dependent
+			buffer_size_min "$[(((2 * $channels_min) * 48) * $DEEPBUFFER_FW_DMA_MS) * 2]"
 		}
 	}
 ]
@@ -83,9 +88,14 @@ IncludeByKey.DEEP_BUF_SPK {
 				Object.PCM.pcm_caps.1 {
 					name $DEEP_BUFFER_PCM_NAME_2
 					formats 'S16_LE,S24_LE,S32_LE'
-					# align with $DEEPBUFFER_FW_DMA_MS
-					period_size_max		65535
-					buffer_size_max		262144
+					# To avoid DMA spinning on a buffer we need bigger
+					# buffer than the host buffer size, let's say twice as
+					# big
+					# (S16_LE, Stereo, 48KHz, DEEPBUFFER_FW_DMA_MS) * 2
+					#
+					# Note: The lower limit for the buffer size is rate
+					#	dependent
+					buffer_size_min "$[(((2 * $channels_min) * 48) * $DEEPBUFFER_FW_DMA_MS) * 2]"
 				}
 			}
 		]