drm: atmel-hlcdc: enable clock before configuring timing engine
authorClaudiu Beznea <claudiu.beznea@microchip.com>
Wed, 18 Dec 2019 12:28:25 +0000 (14:28 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 11 Feb 2020 12:35:35 +0000 (04:35 -0800)
commitd065ae83dff83cd293b7121b5aaa6c24d7acd6ec
treeaad4d91b13ec1122291cb04795e83cc6b2a11052
parent6421785d17e1996ff421c569fefe3273c0e09013
drm: atmel-hlcdc: enable clock before configuring timing engine

commit 2c1fb9d86f6820abbfaa38a6836157c76ccb4e7b upstream.

Changing pixel clock source without having this clock source enabled
will block the timing engine and the next operations after (in this case
setting ATMEL_HLCDC_CFG(5) settings in atmel_hlcdc_crtc_mode_set_nofb()
will fail). It is recomended (although in datasheet this is not present)
to actually enabled pixel clock source before doing any changes on timing
enginge (only SAM9X60 datasheet specifies that the peripheral clock and
pixel clock must be enabled before using LCD controller).

Fixes: 1a396789f65a ("drm: add Atmel HLCDC Display Controller support")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: <stable@vger.kernel.org> # v4.0+
Link: https://patchwork.freedesktop.org/patch/msgid/1576672109-22707-3-git-send-email-claudiu.beznea@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c