From patchwork Thu Feb 20 15:55:32 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thierry Reding X-Patchwork-Id: 322241 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id D2D842C00BE for ; Fri, 21 Feb 2014 02:55:44 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754493AbaBTPzo (ORCPT ); Thu, 20 Feb 2014 10:55:44 -0500 Received: from mail-bk0-f42.google.com ([209.85.214.42]:45781 "EHLO mail-bk0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754469AbaBTPzn (ORCPT ); Thu, 20 Feb 2014 10:55:43 -0500 Received: by mail-bk0-f42.google.com with SMTP id 6so676340bkj.29 for ; Thu, 20 Feb 2014 07:55:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=TBNp6AGeBVryJY8AGUmR5166GQ0KfhRT3sBGMqnqCo0=; b=EHjJ+32nDxTidDzX4GG8+y+JlF6b7yd9fEctYEa+lA9FXgeLYzIoB3cXM4u6DT54Ib eJnBclk/LZ2Ivfr1E75xq1odc+gTvU/BXCgA8VWC13EW22iP1KA2ePyzN+k6knNyBPux GvnP6pO6gbl7fiBk47KjZmtWwO86Lls8Jsp4HK7ALRBjhn5BXZU67r56yK8jlvUqIWvS /oW0WddN23cbGvxxMgDok79OpBx0P7fWcTYV2n+GJYaZYqYu17/Q2Ixx06TNIFsyXOuw M2NxjHYR12Ffzwne5g3Do8s7VHwnzhxVjBUmHyTwbC8xDoTd6+hKJGVVx/THHpYkKCB3 Kk4w== X-Received: by 10.204.61.131 with SMTP id t3mr824439bkh.38.1392911742458; Thu, 20 Feb 2014 07:55:42 -0800 (PST) Received: from localhost (port-49090.pppoe.wtnet.de. [46.59.192.91]) by mx.google.com with ESMTPSA id mc2sm4051221bkb.12.2014.02.20.07.55.41 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 20 Feb 2014 07:55:41 -0800 (PST) From: Thierry Reding To: dri-devel@lists.freedesktop.org Cc: Jani Nikula , Daniel Vetter , Alex Deucher , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , intel-gfx@lists.freedesktop.org, linux-tegra@vger.kernel.org Subject: [PATCH v5 3/5] drm/dp: Add DisplayPort link helpers Date: Thu, 20 Feb 2014 16:55:32 +0100 Message-Id: <1392911734-6689-4-git-send-email-thierry.reding@gmail.com> X-Mailer: git-send-email 1.8.4.2 In-Reply-To: <1392911734-6689-1-git-send-email-thierry.reding@gmail.com> References: <1392911734-6689-1-git-send-email-thierry.reding@gmail.com> Sender: linux-tegra-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-tegra@vger.kernel.org From: Thierry Reding Add a helper to probe a DP link (read out the supported DPCD revision, maximum rate, link count and capabilities) as well as power up the DP link and configure it accordingly. Reviewed-by: Alex Deucher Reviewed-by: Jani Nikula Signed-off-by: Thierry Reding --- Changes in v5: - export helpers Changes in v4: - fix a couple of typos in comments as pointed out by Alex Deucher Changes in v3: - split into drm_dp_link_power_up() and drm_dp_link_configure() - do not change sink state for DPCD versions earlier than 1.1 - sleep for 1-2 ms after setting local sink to D0 state - read and write consecutive registers where possible - read DPCD revision when link is probed - remove duplicate kerneldoc drivers/gpu/drm/drm_dp_helper.c | 97 +++++++++++++++++++++++++++++++++++++++++ include/drm/drm_dp_helper.h | 17 ++++++++ 2 files changed, 114 insertions(+) diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 84262ed64ce7..177ac7bd1851 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -472,3 +472,100 @@ 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() and drm_dp_link_configure() to power up and + * 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 values[3]; + int err; + + memset(link, 0, sizeof(*link)); + + err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values)); + if (err < 0) + return err; + + link->revision = values[0]; + link->rate = drm_dp_bw_code_to_link_rate(values[1]); + link->num_lanes = values[2] & DP_MAX_LANE_COUNT_MASK; + + if (values[2] & DP_ENHANCED_FRAME_CAP) + link->capabilities |= DP_LINK_CAP_ENHANCED_FRAMING; + + return 0; +} +EXPORT_SYMBOL(drm_dp_link_probe); + +/** + * drm_dp_link_power_up() - power up 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; + + /* DP_SET_POWER register is only available on DPCD v1.1 and later */ + if (link->revision < 0x11) + return 0; + + 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, DP_SET_POWER, value); + if (err < 0) + return err; + + /* + * According to the DP 1.1 specification, a "Sink Device must exit the + * power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink + * Control Field" (register 0x600). + */ + usleep_range(1000, 2000); + + return 0; +} +EXPORT_SYMBOL(drm_dp_link_power_up); + +/** + * drm_dp_link_configure() - 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_configure(struct drm_dp_aux *aux, struct drm_dp_link *link) +{ + u8 values[2]; + int err; + + values[0] = drm_dp_link_rate_to_bw_code(link->rate); + values[1] = link->num_lanes; + + if (link->capabilities & DP_LINK_CAP_ENHANCED_FRAMING) + values[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN; + + err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, values, sizeof(values)); + if (err < 0) + return err; + + return 0; +} +EXPORT_SYMBOL(drm_dp_link_configure); diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 8759ce6ce97f..17b3a8a5ff38 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -301,6 +301,7 @@ #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) @@ -490,4 +491,20 @@ static inline ssize_t drm_dp_dpcd_writeb(struct drm_dp_aux *aux, 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 char revision; + unsigned int rate; + unsigned int num_lanes; + unsigned long capabilities; +}; + +int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link); +int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link); +int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link); + #endif /* _DRM_DP_HELPER_H_ */