linux-kernel - [PATCH v2 07/11] drm/tidss: Add simple K2G manual reset

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Message-Id: <20231109-tidss-probe-v2-7-ac91b5ea35c0@ideasonboard.com>
Date:   Thu, 09 Nov 2023 09:38:00 +0200
From:   Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To:     Aradhya Bhatia <a-bhatia1@...com>,
        Devarsh Thakkar <devarsht@...com>,
        Jyri Sarha <jyri.sarha@....fi>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Francesco Dolcini <francesco@...cini.it>,
        Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Subject: [PATCH v2 07/11] drm/tidss: Add simple K2G manual reset

K2G display controller does not support soft reset, but we can do the
most important steps manually: mask the IRQs and disable the VPs.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
---
 drivers/gpu/drm/tidss/tidss_dispc.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
index c82fd5bc9be4..a5c0b72596e8 100644
--- a/drivers/gpu/drm/tidss/tidss_dispc.c
+++ b/drivers/gpu/drm/tidss/tidss_dispc.c
@@ -2702,14 +2702,28 @@ static void dispc_init_errata(struct dispc_device *dispc)
 	}
 }
 
+/*
+ * K2G display controller does not support soft reset, so we do a basic manual
+ * reset here: make sure the IRQs are masked and VPs are disabled.
+ */
+static void dispc_softreset_k2g(struct dispc_device *dispc)
+{
+	dispc_set_irqenable(dispc, 0);
+	dispc_read_and_clear_irqstatus(dispc);
+
+	for (unsigned int vp_idx = 0; vp_idx < dispc->feat->num_vps; ++vp_idx)
+		VP_REG_FLD_MOD(dispc, vp_idx, DISPC_VP_CONTROL, 0, 0, 0);
+}
+
 static int dispc_softreset(struct dispc_device *dispc)
 {
 	u32 val;
 	int ret;
 
-	/* K2G display controller does not support soft reset */
-	if (dispc->feat->subrev == DISPC_K2G)
+	if (dispc->feat->subrev == DISPC_K2G) {
+		dispc_softreset_k2g(dispc);
 		return 0;
+	}
 
 	/* Soft reset */
 	REG_FLD_MOD(dispc, DSS_SYSCONFIG, 1, 1, 1);

-- 
2.34.1