From acd8f414c957406c8272cbc380dd50fea945dcf1 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 17 Jun 2016 09:33:18 +0100 Subject: drm: Minimally initialise drm_dp_aux MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When trying to split up the initialisation phase and the registration phase, one immediate problem encountered is trying to use our own i2c devices before registration with userspace (to read EDID during device discovery). drm_dp_aux in particular only offers an interface for setting up the device *after* we have exposed the connector via sysfs. In order to break the chicken-and-egg problem, export drm_dp_aux_init() to minimally prepare the i2c device for internal use before drm_connector_register(). Signed-off-by: Chris Wilson Cc: Dave Airlie Cc: Rafael Antognolli Cc: Ville Syrjälä Cc: dri-devel@lists.freedesktop.org [danvet: Amend kerneldoc slightly.] Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1466152398-20157-3-git-send-email-chris@chris-wilson.co.uk --- drivers/gpu/drm/drm_dp_helper.c | 28 +++++++++++++++++++++++----- 1 file changed, 23 insertions(+), 5 deletions(-) (limited to 'drivers/gpu/drm/drm_dp_helper.c') diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 4b088afa21b2..091053e995e5 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -791,15 +791,16 @@ static void unlock_bus(struct i2c_adapter *i2c, unsigned int flags) } /** - * drm_dp_aux_register() - initialise and register aux channel + * drm_dp_aux_init() - minimally initialise an aux channel * @aux: DisplayPort AUX channel * - * Returns 0 on success or a negative error code on failure. + * If you need to use the drm_dp_aux's i2c adapter prior to registering it + * with the outside world, call drm_dp_aux_init() first. You must still + * call drm_dp_aux_register() once the connector has been registered to + * allow userspace access to the auxiliary DP channel. */ -int drm_dp_aux_register(struct drm_dp_aux *aux) +void drm_dp_aux_init(struct drm_dp_aux *aux) { - int ret; - mutex_init(&aux->hw_mutex); aux->ddc.algo = &drm_dp_i2c_algo; @@ -809,6 +810,23 @@ int drm_dp_aux_register(struct drm_dp_aux *aux) aux->ddc.lock_bus = lock_bus; aux->ddc.trylock_bus = trylock_bus; aux->ddc.unlock_bus = unlock_bus; +} +EXPORT_SYMBOL(drm_dp_aux_init); + +/** + * drm_dp_aux_register() - initialise and register aux channel + * @aux: DisplayPort AUX channel + * + * Automatically calls drm_dp_aux_init() if this hasn't been done yet. + * + * Returns 0 on success or a negative error code on failure. + */ +int drm_dp_aux_register(struct drm_dp_aux *aux) +{ + int ret; + + if (!aux->ddc.algo) + drm_dp_aux_init(aux); aux->ddc.class = I2C_CLASS_DDC; aux->ddc.owner = THIS_MODULE; -- cgit v1.2.3-59-g8ed1b