Use single memcmp to determine if matrix changed. (#13064)

* Use memcmp to determine if matrix changed.

* Firmware size issues.

* Add documentation for the lack of need of MATRIX_ROW_PINS/MATRIX_COL_PINS, when overriding low-level matrix functions.

2 files changed, 11 insertions, 0 deletions

diff --git a/docs/config_options.md b/docs/config_options.md
index d0f0b316e0..26fe8cea55 100644
--- a/docs/config_options.md
+++ b/docs/config_options.md
@@ -51,8 +51,10 @@ This is a C header file that is one of the first things included, and will persi
   * the number of columns in your keyboard's matrix
 * `#define MATRIX_ROW_PINS { D0, D5, B5, B6 }`
   * pins of the rows, from top to bottom
+  * may be omitted by the keyboard designer if matrix reads are handled in an alternate manner. See [low-level matrix overrides](custom_quantum_functions.md?id=low-level-matrix-overrides) for more information.
 * `#define MATRIX_COL_PINS { F1, F0, B0, C7, F4, F5, F6, F7, D4, D6, B4, D7 }`
   * pins of the columns, from left to right
+  * may be omitted by the keyboard designer if matrix reads are handled in an alternate manner. See [low-level matrix overrides](custom_quantum_functions.md?id=low-level-matrix-overrides) for more information.
 * `#define MATRIX_IO_DELAY 30`
   * the delay in microseconds when between changing matrix pin state and reading values
 * `#define UNUSED_PINS { D1, D2, D3, B1, B2, B3 }`
@@ -280,6 +282,7 @@ There are a few different ways to set handedness for split keyboards (listed in
 * `#define MATRIX_ROW_PINS_RIGHT { <row pins> }`
 * `#define MATRIX_COL_PINS_RIGHT { <col pins> }`
   * If you want to specify a different pinout for the right half than the left half, you can define `MATRIX_ROW_PINS_RIGHT`/`MATRIX_COL_PINS_RIGHT`. Currently, the size of `MATRIX_ROW_PINS` must be the same as `MATRIX_ROW_PINS_RIGHT` and likewise for the definition of columns.
+  * may be omitted by the keyboard designer if matrix reads are handled in an alternate manner. See [low-level matrix overrides](custom_quantum_functions.md?id=low-level-matrix-overrides) for more information.
 
 * `#define DIRECT_PINS_RIGHT { { F1, F0, B0, C7 }, { F4, F5, F6, F7 } }`
   * If you want to specify a different direct pinout for the right half than the left half, you can define `DIRECT_PINS_RIGHT`. Currently, the size of `DIRECT_PINS` must be the same as `DIRECT_PINS_RIGHT`.
diff --git a/docs/custom_quantum_functions.md b/docs/custom_quantum_functions.md
index 694b421e79..30c637bb49 100644
--- a/docs/custom_quantum_functions.md
+++ b/docs/custom_quantum_functions.md
@@ -144,6 +144,14 @@ This is useful for setting up stuff that you may need elsewhere, but isn't hardw
 * Keyboard/Revision: `void matrix_init_kb(void)`
 * Keymap: `void matrix_init_user(void)`
 
+### Low-level Matrix Overrides Function Documentation :id=low-level-matrix-overrides
+
+* GPIO pin initialisation: `void matrix_init_pins(void)`
+  * This needs to perform the low-level initialisation of all row and column pins. By default this will initialise the input/output state of each of the GPIO pins listed in `MATRIX_ROW_PINS` and `MATRIX_COL_PINS`, based on whether or not the keyboard is set up for `ROW2COL`, `COL2ROW`, or `DIRECT_PINS`. Should the keyboard designer override this function, no initialisation of pin state will occur within QMK itself, instead deferring to the keyboard's override.
+* `COL2ROW`-based row reads: `void matrix_read_rows_on_col(matrix_row_t current_matrix[], uint8_t current_col)`
+* `ROW2COL`-based column reads: `void matrix_read_cols_on_row(matrix_row_t current_matrix[], uint8_t current_row)`
+* `DIRECT_PINS`-based reads: `void matrix_read_cols_on_row(matrix_row_t current_matrix[], uint8_t current_row)`
+  * These three functions need to perform the low-level retrieval of matrix state of relevant input pins, based on the matrix type. Only one of the functions should be implemented, if needed. By default this will iterate through `MATRIX_ROW_PINS` and `MATRIX_COL_PINS`, configuring the inputs and outputs based on whether or not the keyboard is set up for `ROW2COL`, `COL2ROW`, or `DIRECT_PINS`. Should the keyboard designer override this function, no manipulation of matrix GPIO pin state will occur within QMK itself, instead deferring to the keyboard's override.
 
 ## Keyboard Post Initialization code