From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B9B94C54E5D for ; Mon, 18 Mar 2024 17:48:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=LM+1KntF8TpszhNrIngrRYJxWcvz0270B05FyaB+Yc4=; b=kS6GotXsaNXXXY ecY48w7uHWckDaLffA9A6Po+a1JEjyx/AyqXwX8RnDD+dfn2vTlv8HUJDZfW0fT7CqXjFGpVZ31os M80h8Sl9065hKxXicVh62yhmvI4VHWwBYP06qdaD5JYWWDYiF5m4rDpWMDdtaXbKSNqKpiPSHjVx6 QQvpvtM9VMEy7mmXSk3u3BcNigrfokQB8bxGLef1CC5NZ4OyHxWn4Iwf5GGiNfPD6WX5fdFtx9Tje 1nsPa8yKBE520Ub3cU3ovLKJc0/QTQNXTmk/s8xjR/P8EyhSlCBzSLQYoSoMxIzj3GOeRMFlEpWBb SwuQoLYbU7n0eOfZaXTw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rmH5h-00000009Wb6-0Lmw; Mon, 18 Mar 2024 17:48:05 +0000 Received: from perceval.ideasonboard.com ([213.167.242.64]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rmH5d-00000009WaR-2w6I for linux-arm-kernel@lists.infradead.org; Mon, 18 Mar 2024 17:48:03 +0000 Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id C4CDA7E9; Mon, 18 Mar 2024 18:47:33 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1710784054; bh=aB4QjsntkdeRYm++bGJb+vjHJ2yqUXdl8ugiaR8bOXE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=keHalQh7OiuMolxVYz3XObQAl6X5j8WHviwPmOqz703pAGv0AVNwvCLXiQG7LjIqG IfxT+TGpn5FZZk31VSmJU1uqFS8UhAcGmXlDh5IeYKurKXpoj4Un1wWQleLOEZt2id 069Z2DlJifS5UlRrJN75rkj7oPIE9hfKsDsMiQsA= Date: Mon, 18 Mar 2024 19:47:57 +0200 From: Laurent Pinchart To: Sean Anderson Cc: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , dri-devel@lists.freedesktop.org, David Airlie , linux-kernel@vger.kernel.org, Michal Simek , linux-arm-kernel@lists.infradead.org, Daniel Vetter Subject: Re: [PATCH 5/6] drm: zynqmp_dp: Optionally ignore DPCD errors Message-ID: <20240318174757.GL13682@pendragon.ideasonboard.com> References: <20240315230916.1759060-1-sean.anderson@linux.dev> <20240315230916.1759060-6-sean.anderson@linux.dev> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240315230916.1759060-6-sean.anderson@linux.dev> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240318_104802_079379_702D989A X-CRM114-Status: GOOD ( 26.89 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Sean, Thank you for the patch. On Fri, Mar 15, 2024 at 07:09:15PM -0400, Sean Anderson wrote: > When testing, it's convenient to be able to ignore DPCD errors if there > is test equipment which can't emulate a DPRX connected to the output. > Add some (currently-unused) options to ignore these errors and just > reconfigure our internal registers as we usually would. This seems to be a problem that is not limited to the ZynqMP DP. Wouldn't it be better to solve it in the DRM DP DPCD helpers instead ? You could expose a parameter on the AUX bus in debugfs to ignore errors, and cause the drm_dp_dpcd_write*() functions to return 0. > Signed-off-by: Sean Anderson > --- > > drivers/gpu/drm/xlnx/zynqmp_dp.c | 37 ++++++++++++++++++++------------ > 1 file changed, 23 insertions(+), 14 deletions(-) > > diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c > index 24043847dab4..040f7b88ee51 100644 > --- a/drivers/gpu/drm/xlnx/zynqmp_dp.c > +++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c > @@ -628,6 +628,7 @@ static void zynqmp_dp_adjust_train(struct zynqmp_dp *dp, > * zynqmp_dp_update_vs_emph - Update the training values > * @dp: DisplayPort IP core structure > * @train_set: A set of training values > + * @ignore_dpcd: Ignore DPCD errors > * > * Update the training values based on the request from sink. The mapped values > * are predefined, and values(vs, pe, pc) are from the device manual. > @@ -635,15 +636,19 @@ static void zynqmp_dp_adjust_train(struct zynqmp_dp *dp, > * Return: 0 if vs and emph are updated successfully, or the error code returned > * by drm_dp_dpcd_write(). > */ > -static int zynqmp_dp_update_vs_emph(struct zynqmp_dp *dp, u8 *train_set) > +static int zynqmp_dp_update_vs_emph(struct zynqmp_dp *dp, u8 *train_set, > + bool ignore_dpcd) > { > unsigned int i; > int ret; > > ret = drm_dp_dpcd_write(&dp->aux, DP_TRAINING_LANE0_SET, train_set, > dp->mode.lane_cnt); > - if (ret < 0) > - return ret; > + if (ret < 0) { > + if (!ignore_dpcd) > + return ret; > + dev_warn(dp->dev, "failed to update vs/emph\n"); > + } > > for (i = 0; i < dp->mode.lane_cnt; i++) { > u32 reg = ZYNQMP_DP_SUB_TX_PHY_PRECURSOR_LANE_0 + i * 4; > @@ -692,7 +697,7 @@ static int zynqmp_dp_link_train_cr(struct zynqmp_dp *dp) > * So, This loop should exit before 512 iterations > */ > for (max_tries = 0; max_tries < 512; max_tries++) { > - ret = zynqmp_dp_update_vs_emph(dp, dp->train_set); > + ret = zynqmp_dp_update_vs_emph(dp, dp->train_set, false); > if (ret) > return ret; > > @@ -757,7 +762,7 @@ static int zynqmp_dp_link_train_ce(struct zynqmp_dp *dp) > return ret; > > for (tries = 0; tries < DP_MAX_TRAINING_TRIES; tries++) { > - ret = zynqmp_dp_update_vs_emph(dp, dp->train_set); > + ret = zynqmp_dp_update_vs_emph(dp, dp->train_set, false); > if (ret) > return ret; > > @@ -785,11 +790,12 @@ static int zynqmp_dp_link_train_ce(struct zynqmp_dp *dp) > * @lane_cnt: The number of lanes to use > * @enhanced: Use enhanced framing > * @downspread: Enable spread-spectrum clocking > + * @ignore_dpcd: Ignore DPCD errors; useful for testing > * > * Return: 0 on success, or -errno on failure > */ > static int zynqmp_dp_setup(struct zynqmp_dp *dp, u8 bw_code, u8 lane_cnt, > - bool enhanced, bool downspread) > + bool enhanced, bool downspread, bool ignore_dpcd) > { > u32 reg; > u8 aux_lane_cnt = lane_cnt; > @@ -812,21 +818,24 @@ static int zynqmp_dp_setup(struct zynqmp_dp *dp, u8 bw_code, u8 lane_cnt, > > ret = drm_dp_dpcd_writeb(&dp->aux, DP_LANE_COUNT_SET, aux_lane_cnt); > if (ret < 0) { > - dev_err(dp->dev, "failed to set lane count\n"); > - return ret; > + dev_warn(dp->dev, "failed to set lane count\n"); > + if (!ignore_dpcd) > + return ret; > } > > ret = drm_dp_dpcd_writeb(&dp->aux, DP_MAIN_LINK_CHANNEL_CODING_SET, > DP_SET_ANSI_8B10B); > if (ret < 0) { > - dev_err(dp->dev, "failed to set ANSI 8B/10B encoding\n"); > - return ret; > + dev_warn(dp->dev, "failed to set ANSI 8B/10B encoding\n"); > + if (!ignore_dpcd) > + return ret; > } > > ret = drm_dp_dpcd_writeb(&dp->aux, DP_LINK_BW_SET, bw_code); > if (ret < 0) { > - dev_err(dp->dev, "failed to set DP bandwidth\n"); > - return ret; > + dev_warn(dp->dev, "failed to set DP bandwidth\n"); > + if (!ignore_dpcd) > + return ret; > } > > zynqmp_dp_write(dp, ZYNQMP_DP_LINK_BW_SET, bw_code); > @@ -860,7 +869,7 @@ static int zynqmp_dp_train(struct zynqmp_dp *dp) > > ret = zynqmp_dp_setup(dp, dp->mode.bw_code, dp->mode.lane_cnt, > drm_dp_enhanced_frame_cap(dp->dpcd), > - dp->dpcd[3] & 0x1); > + dp->dpcd[3] & 0x1, false); > if (ret) > return ret; > > @@ -877,7 +886,7 @@ static int zynqmp_dp_train(struct zynqmp_dp *dp) > ret = drm_dp_dpcd_writeb(&dp->aux, DP_TRAINING_PATTERN_SET, > DP_TRAINING_PATTERN_DISABLE); > if (ret < 0) { > - dev_err(dp->dev, "failed to disable training pattern\n"); > + dev_warn(dp->dev, "failed to disable training pattern\n"); > return ret; > } > zynqmp_dp_write(dp, ZYNQMP_DP_TRAINING_PATTERN_SET, -- Regards, Laurent Pinchart _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel