clocksource/drivers/timer-ti-dm: Drop bogus omap_dm_timer_of_set_source()

The function omap_dm_timer_of_set_source() was originally added in
commit 31a7448f ("ARM: OMAP: dmtimer: Add clock source from DT"),
and is designed to set a clock source from DT using the clocks property
of a timer node. This design choice is okay for clk provider nodes but
otherwise is a bad design as typically the clocks property is used to
specify the functional clocks for a device, and not its parents.

The timer nodes now all define a timer functional clock after the
conversion to ti-sysc and the new clkctrl layout, and this results
in an attempt to set the same functional clock as its parent when a
consumer driver attempts to acquire any of these timers in the
omap_dm_timer_prepare() function. This was masked and worked around
in commit 983a5a43 ("clocksource: timer-ti-dm: Fix pwm dmtimer
usage of fck reparenting"). Fix all of this by simply dropping the
entire function.

Any DT configuration of clock sources should be achieved using
assigned-clocks and assigned-clock-parents properties provided
by the Common Clock Framework.

Cc: Tony Lindgren <tony@atomide.com>
Cc: Tero Kristo <t-kristo@ti.com>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: H. Nikolaus Schaller <hns@goldelico.com>
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: Keerthy <j-keerthy@ti.com>
Cc: Ladislav Michl <ladis@linux-mips.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Suman Anna <s-anna@ti.com>
Tested-by: Lokesh Vutla <lokeshvutla@ti.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20200213053504.22638-1-s-anna@ti.com

drivers/clocksource/timer-ti-dm.c

@@ -138,35 +138,6 @@ static int omap_dm_timer_reset(struct omap_dm_timer *timer)
 	return 0;
 }
 
-static int omap_dm_timer_of_set_source(struct omap_dm_timer *timer)
-{
-	int ret;
-	struct clk *parent;
-
-	/*
-	 * FIXME: OMAP1 devices do not use the clock framework for dmtimers so
-	 * do not call clk_get() for these devices.
-	 */
-	if (!timer->fclk)
-		return -ENODEV;
-
-	parent = clk_get(&timer->pdev->dev, NULL);
-	if (IS_ERR(parent))
-		return -ENODEV;
-
-	/* Bail out if both clocks point to fck */
-	if (clk_is_match(parent, timer->fclk))
-		return 0;
-
-	ret = clk_set_parent(timer->fclk, parent);
-	if (ret < 0)
-		pr_err("%s: failed to set parent\n", __func__);
-
-	clk_put(parent);
-
-	return ret;
-}
-
 static int omap_dm_timer_set_source(struct omap_dm_timer *timer, int source)
 {
 	int ret;
@@ -276,9 +247,7 @@ static int omap_dm_timer_prepare(struct omap_dm_timer *timer)
 	__omap_dm_timer_enable_posted(timer);
 	omap_dm_timer_disable(timer);
 
-	rc = omap_dm_timer_of_set_source(timer);
-	if (rc == -ENODEV)
-		return omap_dm_timer_set_source(timer, OMAP_TIMER_SRC_32_KHZ);
+	rc = omap_dm_timer_set_source(timer, OMAP_TIMER_SRC_32_KHZ);
 
 	return rc;
 }