Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966554AbcDLVdN (ORCPT ); Tue, 12 Apr 2016 17:33:13 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:50745 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966379AbcDLUxg (ORCPT ); Tue, 12 Apr 2016 16:53:36 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Rob Clark , Dave Airlie , Kamal Mostafa Subject: [PATCH 4.2.y-ckt 27/70] drm/dp: move hw_mutex up the call stack Date: Tue, 12 Apr 2016 13:52:12 -0700 Message-Id: <1460494375-30070-28-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1460494375-30070-1-git-send-email-kamal@canonical.com> References: <1460494375-30070-1-git-send-email-kamal@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Extended-Stable: 4.2 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3732 Lines: 127 4.2.8-ckt8 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Rob Clark commit 7779c5e23c5132c22a219f1f5554ef81dd15ee91 upstream. 1) don't let other threads trying to bang on aux channel interrupt the defer timeout/logic 2) don't let other threads interrupt the i2c over aux logic Technically, according to people who actually have the DP spec, this should not be required. In practice, it makes some troublesome Dell monitor (and perhaps others) work, so probably a case of "It's compliant if it works with windows" on the hw vendor's part.. v2: rebased to come before DPCD/AUX logging patch for easier backport to stable branches. Reported-by: Dave Wysochanski Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1274157 Signed-off-by: Rob Clark Reviewed-by: Ville Syrjälä Reviewed-by: Daniel Vetter Signed-off-by: Dave Airlie Signed-off-by: Kamal Mostafa --- drivers/gpu/drm/drm_dp_helper.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 80a02a4..e62ac37 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -176,7 +176,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, { struct drm_dp_aux_msg msg; unsigned int retry; - int err; + int err = 0; memset(&msg, 0, sizeof(msg)); msg.address = offset; @@ -184,6 +184,8 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, msg.buffer = buffer; msg.size = size; + mutex_lock(&aux->hw_mutex); + /* * The specification doesn't give any recommendation on how often to * retry native transactions. We used to retry 7 times like for @@ -192,25 +194,24 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, */ for (retry = 0; retry < 32; retry++) { - mutex_lock(&aux->hw_mutex); err = aux->transfer(aux, &msg); - mutex_unlock(&aux->hw_mutex); if (err < 0) { if (err == -EBUSY) continue; - return err; + goto unlock; } switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) { case DP_AUX_NATIVE_REPLY_ACK: if (err < size) - return -EPROTO; - return err; + err = -EPROTO; + goto unlock; case DP_AUX_NATIVE_REPLY_NACK: - return -EIO; + err = -EIO; + goto unlock; case DP_AUX_NATIVE_REPLY_DEFER: usleep_range(400, 500); @@ -219,7 +220,11 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, } DRM_DEBUG_KMS("too many retries, giving up\n"); - return -EIO; + err = -EIO; + +unlock: + mutex_unlock(&aux->hw_mutex); + return err; } /** @@ -441,9 +446,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) * before giving up the AUX transaction. */ for (retry = 0, defer_i2c = 0; retry < (7 + defer_i2c); retry++) { - mutex_lock(&aux->hw_mutex); ret = aux->transfer(aux, msg); - mutex_unlock(&aux->hw_mutex); if (ret < 0) { if (ret == -EBUSY) continue; @@ -570,6 +573,8 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, memset(&msg, 0, sizeof(msg)); + mutex_lock(&aux->hw_mutex); + for (i = 0; i < num; i++) { msg.address = msgs[i].addr; msg.request = (msgs[i].flags & I2C_M_RD) ? @@ -613,6 +618,8 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, msg.size = 0; (void)drm_dp_i2c_do_msg(aux, &msg); + mutex_unlock(&aux->hw_mutex); + return err; } -- 2.7.4