linux-kernel - [PATCH v2 01/13] drm/mediatek: add refcount for DPI power on/off

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 5 Sep 2018 16:31:34 +0800
From:   Bibby Hsieh <bibby.hsieh@...iatek.com>
To:     David Airlie <airlied@...ux.ie>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        <dri-devel@...ts.freedesktop.org>,
        <linux-mediatek@...ts.infradead.org>
CC:     Yingjoe Chen <yingjoe.chen@...iatek.com>,
        Cawa Cheng <cawa.cheng@...iatek.com>,
        Daniel Kurtz <djkurtz@...omium.org>,
        Bibby Hsieh <bibby.hsieh@...iatek.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        YT Shen <yt.shen@...iatek.com>,
        Thierry Reding <thierry.reding@...il.com>,
        CK Hu <ck.hu@...iatek.com>, Mao Huang <littlecvr@...omium.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        Sascha Hauer <kernel@...gutronix.de>,
        chunhui dai <chunhui.dai@...iatek.com>
Subject: [PATCH v2 01/13] drm/mediatek: add refcount for DPI power on/off

From: chunhui dai <chunhui.dai@...iatek.com>

add refcount for DPI power on/off to protect the flow

Signed-off-by: chunhui dai <chunhui.dai@...iatek.com>
---
 drivers/gpu/drm/mediatek/mtk_dpi.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
index 6c0ea39d5739..d9373e67d328 100644
--- a/drivers/gpu/drm/mediatek/mtk_dpi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
@@ -77,6 +77,7 @@ struct mtk_dpi {
 	enum mtk_dpi_out_bit_num bit_num;
 	enum mtk_dpi_out_channel_swap channel_swap;
 	bool power_sta;
+	int refcount;
 	u8 power_ctl;
 };
 
@@ -369,6 +370,12 @@ static void mtk_dpi_config_color_format(struct mtk_dpi *dpi,
 
 static void mtk_dpi_power_off(struct mtk_dpi *dpi, enum mtk_dpi_power_ctl pctl)
 {
+	if (WARN_ON(dpi->refcount == 0))
+		return;
+
+	if (--dpi->refcount != 0)
+		return;
+
 	dpi->power_ctl &= ~pctl;
 
 	if ((dpi->power_ctl & DPI_POWER_START) ||
@@ -388,14 +395,17 @@ static int mtk_dpi_power_on(struct mtk_dpi *dpi, enum mtk_dpi_power_ctl pctl)
 {
 	int ret;
 
+	if (++dpi->refcount != 1)
+		return 0;
+
 	dpi->power_ctl |= pctl;
 
 	if (!(dpi->power_ctl & DPI_POWER_START) &&
 	    !(dpi->power_ctl & DPI_POWER_ENABLE))
-		return 0;
+		goto err_refcount;
 
 	if (dpi->power_sta)
-		return 0;
+		goto err_refcount;
 
 	ret = clk_prepare_enable(dpi->engine_clk);
 	if (ret) {
@@ -417,6 +427,8 @@ static int mtk_dpi_power_on(struct mtk_dpi *dpi, enum mtk_dpi_power_ctl pctl)
 	clk_disable_unprepare(dpi->engine_clk);
 err_eng:
 	dpi->power_ctl &= ~pctl;
+err_refcount:
+	dpi->refcount--;
 	return ret;
 }
 
-- 
2.12.5.2.gbdf23ab