extmod: Fix getting sector size when the max and min sizes are the

same.

Also switch the max size back to 512 for atmel-samd to save ram.

Author: tannewt

atmel-samd/mpconfigport.h

@@ -70,7 +70,9 @@
 #define MICROPY_FATFS_VOLUMES          (4)
 #define MICROPY_FATFS_MULTI_PARTITION  (1)
 #define MICROPY_FSUSERMOUNT            (1)
-#define MICROPY_FATFS_MAX_SS           (4096)
+// Only enable this if you really need it. It allocates a byte cache of this
+// size.
+// #define MICROPY_FATFS_MAX_SS           (4096)
 
 #define FLASH_BLOCK_SIZE            (512)
 

extmod/vfs_fat.c

@@ -278,7 +278,11 @@ STATIC mp_obj_t fat_vfs_statvfs(mp_obj_t vfs_in, mp_obj_t path_in) {
 
     mp_obj_tuple_t *t = MP_OBJ_TO_PTR(mp_obj_new_tuple(10, NULL));
 
-    t->items[0] = MP_OBJ_NEW_SMALL_INT(fatfs->csize * fatfs->ssize); // f_bsize
+    #if _MIN_SS != _MAX_SS
+        t->items[0] = MP_OBJ_NEW_SMALL_INT(fatfs->csize * fatfs->ssize); // f_bsize
+    #else
+        t->items[0] = MP_OBJ_NEW_SMALL_INT(fatfs->csize * _MIN_SS); // f_bsize
+    #endif
     t->items[1] = t->items[0]; // f_frsize
     t->items[2] = MP_OBJ_NEW_SMALL_INT((fatfs->n_fatent - 2) * fatfs->csize); // f_blocks
     t->items[3] = MP_OBJ_NEW_SMALL_INT(nclst); // f_bfree