drm/bridge: sil_sii8620: make remote control optional.

commit d6abe6df ("drm/bridge: sil_sii8620: do not have a dependency
of RC_CORE") changed the driver to select both RC_CORE and INPUT.
However, this causes problems with other drivers, in particular an input
driver that depends on MFD_INTEL_LPSS_PCI (to be added in a separate
commit):

  drivers/clk/Kconfig:9:error: recursive dependency detected!
  drivers/clk/Kconfig:9:        symbol COMMON_CLK is selected by MFD_INTEL_LPSS
  drivers/mfd/Kconfig:566:      symbol MFD_INTEL_LPSS is selected by MFD_INTEL_LPSS_PCI
  drivers/mfd/Kconfig:580:      symbol MFD_INTEL_LPSS_PCI is implied by KEYBOARD_APPLESPI
  drivers/input/keyboard/Kconfig:73:    symbol KEYBOARD_APPLESPI depends on INPUT
  drivers/input/Kconfig:8:      symbol INPUT is selected by DRM_SIL_SII8620
  drivers/gpu/drm/bridge/Kconfig:83:    symbol DRM_SIL_SII8620 depends on DRM_BRIDGE
  drivers/gpu/drm/bridge/Kconfig:1:     symbol DRM_BRIDGE is selected by DRM_PL111
  drivers/gpu/drm/pl111/Kconfig:1:      symbol DRM_PL111 depends on COMMON_CLK

According to the docs and general consensus, select should only be used
for non user-visible symbols, but both RC_CORE and INPUT are
user-visible. Furthermore almost all other references to INPUT
throughout the kernel config are depends, not selects. For this reason
the first part of this change reverts the commit.

In order to address the original reason for the commit, namely
that not all boards use the remote controller functionality and hence
should not need have to deal with RC_CORE, the second part of this
change now makes the remote control support in the driver optional and
contingent on RC_CORE being defined. And with this the hard dependency
on INPUT also goes away as that is only needed if RC_CORE is defined
(which in turn already depends on INPUT).

CC: Inki Dae <inki.dae@samsung.com>
CC: Andrzej Hajda <a.hajda@samsung.com>
CC: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
CC: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Ronald Tschalär <ronald@innovation.ch>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
[a.hajda: applied fixup provided by Arnd Bergmann]
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190419081926.13567-2-ronald@innovation.ch

drivers/gpu/drm/bridge/Kconfig

@@ -87,8 +87,7 @@ config DRM_SIL_SII8620
 	depends on OF
 	select DRM_KMS_HELPER
 	imply EXTCON
-	select INPUT
-	select RC_CORE
+	depends on RC_CORE || !RC_CORE
 	help
 	  Silicon Image SII8620 HDMI/MHL bridge chip driver.
 

drivers/gpu/drm/bridge/sil-sii8620.c

@@ -1760,10 +1760,8 @@ static bool sii8620_rcp_consume(struct sii8620 *ctx, u8 scancode)
 
 	scancode &= MHL_RCP_KEY_ID_MASK;
 
-	if (!ctx->rc_dev) {
-		dev_dbg(ctx->dev, "RCP input device not initialized\n");
+	if (!IS_ENABLED(CONFIG_RC_CORE) || !ctx->rc_dev)
 		return false;
-	}
 
 	if (pressed)
 		rc_keydown(ctx->rc_dev, RC_PROTO_CEC, scancode, 0);
@@ -2100,6 +2098,9 @@ static void sii8620_init_rcp_input_dev(struct sii8620 *ctx)
 	struct rc_dev *rc_dev;
 	int ret;
 
+	if (!IS_ENABLED(CONFIG_RC_CORE))
+		return;
+
 	rc_dev = rc_allocate_device(RC_DRIVER_SCANCODE);
 	if (!rc_dev) {
 		dev_err(ctx->dev, "Failed to allocate RC device\n");
@@ -2214,6 +2215,9 @@ static void sii8620_detach(struct drm_bridge *bridge)
 {
 	struct sii8620 *ctx = bridge_to_sii8620(bridge);
 
+	if (!IS_ENABLED(CONFIG_RC_CORE))
+		return;
+
 	rc_unregister_device(ctx->rc_dev);
 }