From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: [PATCH v2 3/4] drm/dp: Add DisplayPort link helpers Date: Tue, 17 Dec 2013 17:20:06 +0100 Message-ID: <1387297207-7643-4-git-send-email-treding@nvidia.com> References: <1387297207-7643-1-git-send-email-treding@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-bk0-f51.google.com (mail-bk0-f51.google.com [209.85.214.51]) by gabe.freedesktop.org (Postfix) with ESMTP id 712ACFCD5F for ; Tue, 17 Dec 2013 08:21:39 -0800 (PST) Received: by mail-bk0-f51.google.com with SMTP id 6so2904535bkj.38 for ; Tue, 17 Dec 2013 08:21:38 -0800 (PST) Received: from localhost (port-6309.pppoe.wtnet.de. [84.46.24.189]) by mx.google.com with ESMTPSA id o5sm13990993bkz.4.2013.12.17.08.21.37 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 17 Dec 2013 08:21:37 -0800 (PST) In-Reply-To: <1387297207-7643-1-git-send-email-treding@nvidia.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dri-devel-bounces@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org To: dri-devel@lists.freedesktop.org List-Id: dri-devel@lists.freedesktop.org Add a helper to probe a DP link (reading out the maximum rate, link count and capabilities) as well as configuring it accordingly. Signed-off-by: Thierry Reding --- drivers/gpu/drm/drm_dp_helper.c | 77 +++++++++++++++++++++++++++++++++++++++++ include/drm/drm_dp_helper.h | 30 ++++++++++++++++ 2 files changed, 107 insertions(+) diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 8111b8e5a8bc..01a8173c6e83 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -478,3 +478,80 @@ int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux, DP_LINK_STATUS_SIZE); } EXPORT_SYMBOL(drm_dp_dpcd_read_link_status); + +/** + * drm_dp_link_probe() - probe a DisplayPort link for capabilities + * @aux: DisplayPort AUX channel + * @link: pointer to structure in which to return link capabilities + * + * The structure filled in by this function can usually be passed directly + * into drm_dp_link_power_up() configure the link based on the link's + * capabilities. + * + * Returns 0 on success or a negative error code on failure. + */ +int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link) +{ + u8 value; + int err; + + memset(link, 0, sizeof(*link)); + + err = drm_dp_dpcd_readb(aux, DP_MAX_LINK_RATE, &value); + if (err < 0) + return err; + + link->rate = drm_dp_bw_code_to_link_rate(value); + + err = drm_dp_dpcd_readb(aux, DP_MAX_LANE_COUNT, &value); + if (err < 0) + return err; + + link->num_lanes = value & DP_MAX_LANE_COUNT_MASK; + + if (value & DP_ENHANCED_FRAME_CAP) + link->capabilities |= DP_LINK_CAP_ENHANCED_FRAMING; + + return 0; +} + +/** + * drm_dp_link_power_up() - power up and configure a DisplayPort link + * @aux: DisplayPort AUX channel + * @link: pointer to a structure containing the link configuration + * + * Returns 0 on success or a negative error code on failure. + */ +int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link) +{ + u8 value; + int err; + + err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value); + if (err < 0) + return err; + + value &= ~DP_SET_POWER_MASK; + value |= DP_SET_POWER_D0; + + err = drm_dp_dpcd_writeb(aux, value, DP_SET_POWER); + if (err < 0) + return err; + + value = drm_dp_link_rate_to_bw_code(link->rate); + + err = drm_dp_dpcd_writeb(aux, value, DP_LINK_BW_SET); + if (err < 0) + return err; + + value = link->num_lanes; + + if (link->capabilities & DP_LINK_CAP_ENHANCED_FRAMING) + value |= DP_LANE_COUNT_ENHANCED_FRAME_EN; + + err = drm_dp_dpcd_writeb(aux, value, DP_LANE_COUNT_SET); + if (err < 0) + return err; + + return 0; +} diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 38cbaef05005..bad9ee11a2e2 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -290,6 +290,7 @@ #define DP_SET_POWER 0x600 # define DP_SET_POWER_D0 0x1 # define DP_SET_POWER_D3 0x2 +# define DP_SET_POWER_MASK 0x3 #define DP_PSR_ERROR_STATUS 0x2006 /* XXX 1.2? */ # define DP_PSR_LINK_CRC_ERROR (1 << 0) @@ -464,4 +465,33 @@ static inline ssize_t drm_dp_dpcd_writeb(struct drm_dp_aux *aux, u8 value, int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux, u8 status[DP_LINK_STATUS_SIZE]); +/* + * DisplayPort link + */ +#define DP_LINK_CAP_ENHANCED_FRAMING (1 << 0) + +struct drm_dp_link { + unsigned int rate; + unsigned int num_lanes; + unsigned long capabilities; +}; + +/** + * drm_dp_link_probe() - probe link properties and capabilities + * @aux: DisplayPort AUX channel + * @link: DisplayPort link + * + * Returns 0 on success or a negative error code on failure. + */ +int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link); + +/** + * drm_dp_link_power_up() - power up a link + * @aux: DisplayPort AUX channel + * @link: DisplayPort link + * + * Returns 0 on success or a negative error code on failure. + */ +int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link); + #endif /* _DRM_DP_HELPER_H_ */ -- 1.8.4.2