Merge tag 'regmap-fix-v7.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap

Pull regmap fix from Mark Brown:
 "A fix from Andy Shevchenko for an issue with caching of page selector
  registers which are located inside the page they are switching"

* tag 'regmap-fix-v7.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap:
  regmap: Synchronize cache for the page selector

Author: torvalds

drivers/base/regmap/regmap.c

@@ -1545,6 +1545,7 @@ static int _regmap_select_page(struct regmap *map, unsigned int *reg,
 			       unsigned int val_num)
 {
 	void *orig_work_buf;
+	unsigned int selector_reg;
 	unsigned int win_offset;
 	unsigned int win_page;
 	bool page_chg;
@@ -1563,10 +1564,31 @@ static int _regmap_select_page(struct regmap *map, unsigned int *reg,
 			return -EINVAL;
 	}
 
-	/* It is possible to have selector register inside data window.
-	   In that case, selector register is located on every page and
-	   it needs no page switching, when accessed alone. */
+	/*
+	 * Calculate the address of the selector register in the corresponding
+	 * data window if it is located on every page.
+	 */
+	page_chg = in_range(range->selector_reg, range->window_start, range->window_len);
+	if (page_chg)
+		selector_reg = range->range_min + win_page * range->window_len +
+			       range->selector_reg - range->window_start;
+
+	/*
+	 * It is possible to have selector register inside data window.
+	 * In that case, selector register is located on every page and it
+	 * needs no page switching, when accessed alone.
+	 *
+	 * Nevertheless we should synchronize the cache values for it.
+	 * This can't be properly achieved if the selector register is
+	 * the first and the only one to be read inside the data window.
+	 * That's why we update it in that case as well.
+	 *
+	 * However, we specifically avoid updating it for the default page,
+	 * when it's overlapped with the real data window, to prevent from
+	 * infinite looping.
+	 */
 	if (val_num > 1 ||
+	    (page_chg && selector_reg != range->selector_reg) ||
 	    range->window_start + win_offset != range->selector_reg) {
 		/* Use separate work_buf during page switching */
 		orig_work_buf = map->work_buf;
@@ -1575,7 +1597,7 @@ static int _regmap_select_page(struct regmap *map, unsigned int *reg,
 		ret = _regmap_update_bits(map, range->selector_reg,
 					  range->selector_mask,
 					  win_page << range->selector_shift,
-					  &page_chg, false);
+					  NULL, false);
 
 		map->work_buf = orig_work_buf;