doc(sdio_slave): add some information of slave protocol

diff --git a/docs/en/api-reference/peripherals/esp_slave_protocol.rst b/docs/en/api-reference/peripherals/esp_slave_protocol.rst
index 04cecca534ac742a421f36b475ee36dfd1290c5f..de3c0596e47996e4eeebe81337b81ceb893d7f57 100644 (file)
--- a/docs/en/api-reference/peripherals/esp_slave_protocol.rst
+++ b/docs/en/api-reference/peripherals/esp_slave_protocol.rst
@@ -35,12 +35,28 @@ FIFO (sending and receiving)
 
 0x090 - 0x1F7FF are reserved for FIFOs.
 
-.. note:: This includes the CMD52 and CMD53 (block mode or byte mode).
+The address of CMD53 is related to the length requested to read from/write to
+the slave in a single transfer:
+
+    *requested length = 0x1F800-address*
+
+The slave will respond with the length according to the length field in
+CMD53, with the data longer than *requested length* filled with 0 (sending)
+or discard (receiving).
+
+.. note:: This includes both the block and the byte mode of CMD53.
 
     The function number should be set to 1, OP Code should be set to 1 (for CMD53).
 
-    The slave will respond with the length according to the length field in CMD53 (1 of CMD52), with the data longer
-    than *requested length* filled with 0 (sending) or discard (receiving).
+    It is allowed to use CMD53 mode combination of block+byte to get higher
+    effeciency when accessing the FIFO by arbitrary length. E.g. The block
+    size is set to 512 by default, you can write/get 1031 bytes of data
+    to/from the FIFO by:
+
+    1. Send CMD53 in block mode, block count=2 (1024 bytes) to address
+       0x1F3F9=0x1F800-**1031**.
+    2. Then send CMD53 in byte mode, byte count=8 (or 7 if your controller
+       supports that) to address 0x1F7F9=0x1F800-**7**.
 
 Interrupts
 ----------

diff --git a/docs/en/api-reference/peripherals/sdio_slave.rst b/docs/en/api-reference/peripherals/sdio_slave.rst
index 4a13693cc9735966b1df86eb0efd3e7a1a1418e7..eb041d424a43808cc8c4fd41a4b0cdc464a110d3 100644 (file)
--- a/docs/en/api-reference/peripherals/sdio_slave.rst
+++ b/docs/en/api-reference/peripherals/sdio_slave.rst
@@ -64,17 +64,17 @@ The SDIO slave driver uses the following terms:
 - Sending: slave to host transfers.
 - Receiving: host to slave transfers.
 
-.. note:: Register names in ESP Rechnical Reference Manual are oriented from the point of view of the host, i.e. 'rx' 
-  registers refer to sending, while 'tx' registers refer to receiving. We're not using `tx` or `rx` in the driver to 
+.. note:: Register names in ESP Rechnical Reference Manual are oriented from the point of view of the host, i.e. 'rx'
+  registers refer to sending, while 'tx' registers refer to receiving. We're not using `tx` or `rx` in the driver to
   avoid ambiguities.
 
 - FIFO: specific address in Function 1 that can be access by CMD53 to read/write large amount of data. The address is
   related to the length requested to read from/write to the slave in a single transfer:
   *requested length* = 0x1F800-address.
 - Ownership: When the driver takes ownership of a buffer, it means the driver can randomly read/write the buffer
-    (mostly by the hardware). The application should not read/write the buffer until the ownership is returned to the
-    application. If the application reads from a buffer owned by a receiving driver, the data read can be random; if
-    the application writes to a buffer owned by a sending driver, the data sent may be corrupted.
+  (usually via DMA). The application should not read/write the buffer until the ownership is returned to the
+  application. If the application reads from a buffer owned by a receiving driver, the data read can be random; if
+  the application writes to a buffer owned by a sending driver, the data sent may be corrupted.
 - Requested length: The length requested in one transfer determined by the FIFO address.
 - Transfer length: The length requested in one transfer determined by the CMD53 byte/block count field.