From patchwork Mon Nov 13 16:43:44 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Walle X-Patchwork-Id: 13454174 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 A628CC4167B for ; Mon, 13 Nov 2023 16:44:02 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id EF15410E3C2; Mon, 13 Nov 2023 16:44:01 +0000 (UTC) Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by gabe.freedesktop.org (Postfix) with ESMTPS id 3D07110E16F for ; Mon, 13 Nov 2023 16:44:00 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 560E8CE1710; Mon, 13 Nov 2023 16:43:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3EF6FC433C8; Mon, 13 Nov 2023 16:43:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699893836; bh=RlU79UoJoYw5u+/7L0jkhh1x9IUQoSb9+SIzJtrRGT0=; h=From:To:Cc:Subject:Date:From; b=W/VU9kEfDnI64dPMSeIJrgX7Jgz8wdAmXGv4AgpSLPeX0ShchR0icbptMTPSHq8ZE mBrt2R8ghk6s8ZnDGECLomg9t+i2yGj+1UUpZbJ+DyaUxAAmdtPB/Ugt8uQ7yhI7m1 3Pp2KB2uLGBFe5Kw7IxchyXGEOj9+0VxTv4+6glbLauPGcOnLe7w/heE8ghyxTlTP6 GEftJIDPtehfjc/CyEpm4H58/L6VFZHKDZGD7zX0QauaNYgTi76QbzO3JZ7vSDKwCj SlFeocSTS0Xcje57aOiLoJSz92R18TVWJhiRjN3uzAHs3abon/eog+8C/lQIBsxFFT oiBEQ2FIWgbTw== From: Michael Walle To: Inki Dae , Jagan Teki , Marek Szyprowski , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , David Airlie , Daniel Vetter , Frieder Schrempf , Tim Harvey , Alexander Stein Subject: [PATCH] drm: bridge: samsung-dsim: Don't use FORCE_STOP_STATE Date: Mon, 13 Nov 2023 17:43:44 +0100 Message-Id: <20231113164344.1612602-1-mwalle@kernel.org> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Michael Walle , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" The FORCE_STOP_STATE bit is unsuitable to force the DSI link into LP-11 mode. It seems the bridge internally queues DSI packets and when the FORCE_STOP_STATE bit is cleared, they are sent in close succession without any useful timing (this also means that the DSI lanes won't go into LP-11 mode). The length of this gibberish varies between 1ms and 5ms. This sometimes breaks an attached bridge (TI SN65DSI84 in this case). In our case, the bridge will fail in about 1 per 500 reboots. The FORCE_STOP_STATE handling was introduced to have the DSI lanes in LP-11 state during the .pre_enable phase. But as it turns out, none of this is needed at all. Between samsung_dsim_init() and samsung_dsim_set_display_enable() the lanes are already in LP-11 mode. The code as it was before commit 20c827683de0 ("drm: bridge: samsung-dsim: Fix init during host transfer") and 0c14d3130654 ("drm: bridge: samsung-dsim: Fix i.MX8M enable flow to meet spec") was correct in this regard. This patch basically reverts both commits. It was tested on an i.MX8M SoC with an SN65DSI84 bridge. The signals were probed and the DSI packets were decoded during initialization and link start-up. After this patch the first DSI packet on the link is a VSYNC packet and the timing is correct. Command mode between .pre_enable and .enable was also briefly tested by a quick hack. There was no DSI link partner which would have responded, but it was made sure the DSI packet was send on the link. As a side note, the command mode seems to just work in HS mode. I couldn't find that the bridge will handle commands in LP mode. Fixes: 20c827683de0 ("drm: bridge: samsung-dsim: Fix init during host transfer") Fixes: 0c14d3130654 ("drm: bridge: samsung-dsim: Fix i.MX8M enable flow to meet spec") Signed-off-by: Michael Walle Reviewed-by: Frieder Schrempf --- Let me know wether this should be two commits each reverting one, but both commits appeared first in kernel 6.5. drivers/gpu/drm/bridge/samsung-dsim.c | 32 ++------------------------- 1 file changed, 2 insertions(+), 30 deletions(-) diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c index cf777bdb25d2..4233a50baac7 100644 --- a/drivers/gpu/drm/bridge/samsung-dsim.c +++ b/drivers/gpu/drm/bridge/samsung-dsim.c @@ -939,10 +939,6 @@ static int samsung_dsim_init_link(struct samsung_dsim *dsi) reg = samsung_dsim_read(dsi, DSIM_ESCMODE_REG); reg &= ~DSIM_STOP_STATE_CNT_MASK; reg |= DSIM_STOP_STATE_CNT(driver_data->reg_values[STOP_STATE_CNT]); - - if (!samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) - reg |= DSIM_FORCE_STOP_STATE; - samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg); reg = DSIM_BTA_TIMEOUT(0xff) | DSIM_LPDR_TIMEOUT(0xffff); @@ -1387,18 +1383,6 @@ static void samsung_dsim_disable_irq(struct samsung_dsim *dsi) disable_irq(dsi->irq); } -static void samsung_dsim_set_stop_state(struct samsung_dsim *dsi, bool enable) -{ - u32 reg = samsung_dsim_read(dsi, DSIM_ESCMODE_REG); - - if (enable) - reg |= DSIM_FORCE_STOP_STATE; - else - reg &= ~DSIM_FORCE_STOP_STATE; - - samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg); -} - static int samsung_dsim_init(struct samsung_dsim *dsi) { const struct samsung_dsim_driver_data *driver_data = dsi->driver_data; @@ -1448,9 +1432,6 @@ static void samsung_dsim_atomic_pre_enable(struct drm_bridge *bridge, ret = samsung_dsim_init(dsi); if (ret) return; - - samsung_dsim_set_display_mode(dsi); - samsung_dsim_set_display_enable(dsi, true); } } @@ -1459,12 +1440,8 @@ static void samsung_dsim_atomic_enable(struct drm_bridge *bridge, { struct samsung_dsim *dsi = bridge_to_dsi(bridge); - if (samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) { - samsung_dsim_set_display_mode(dsi); - samsung_dsim_set_display_enable(dsi, true); - } else { - samsung_dsim_set_stop_state(dsi, false); - } + samsung_dsim_set_display_mode(dsi); + samsung_dsim_set_display_enable(dsi, true); dsi->state |= DSIM_STATE_VIDOUT_AVAILABLE; } @@ -1477,9 +1454,6 @@ static void samsung_dsim_atomic_disable(struct drm_bridge *bridge, if (!(dsi->state & DSIM_STATE_ENABLED)) return; - if (!samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) - samsung_dsim_set_stop_state(dsi, true); - dsi->state &= ~DSIM_STATE_VIDOUT_AVAILABLE; } @@ -1781,8 +1755,6 @@ static ssize_t samsung_dsim_host_transfer(struct mipi_dsi_host *host, if (ret) return ret; - samsung_dsim_set_stop_state(dsi, false); - ret = mipi_dsi_create_packet(&xfer.packet, msg); if (ret < 0) return ret;