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[92.176.231.205]) by smtp.gmail.com with ESMTPSA id k5-20020adfd845000000b002bdd96d88b4sm23716899wrl.75.2023.01.21.11.09.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 21 Jan 2023 11:09:35 -0800 (PST) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Subject: [PATCH] drm/ssd130x: Silence a `dubious: x & !y` warning Date: Sat, 21 Jan 2023 20:09:30 +0100 Message-Id: <20230121190930.2804224-1-javierm@redhat.com> X-Mailer: git-send-email 2.39.0 MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com 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: dri-devel@lists.freedesktop.org, Javier Martinez Canillas , Thomas Zimmermann Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" The sparse tool complains with the following warning: $ make M=drivers/gpu/drm/solomon/ C=2 CC [M] drivers/gpu/drm/solomon/ssd130x.o CHECK drivers/gpu/drm/solomon/ssd130x.c drivers/gpu/drm/solomon/ssd130x.c:363:21: warning: dubious: x & !y This seems to be a false positive in my opinion but still we can silence the tool while making the code easier to read. Let's also add a comment, to explain why the "com_seq" logical not is used rather than its value. Reported-by: Thomas Zimmermann Signed-off-by: Javier Martinez Canillas Reviewed-by: Thomas Zimmermann --- drivers/gpu/drm/solomon/ssd130x.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c index c3bf3a18302e..b16330a8b624 100644 --- a/drivers/gpu/drm/solomon/ssd130x.c +++ b/drivers/gpu/drm/solomon/ssd130x.c @@ -81,7 +81,7 @@ #define SSD130X_SET_PRECHARGE_PERIOD2_MASK GENMASK(7, 4) #define SSD130X_SET_PRECHARGE_PERIOD2_SET(val) FIELD_PREP(SSD130X_SET_PRECHARGE_PERIOD2_MASK, (val)) #define SSD130X_SET_COM_PINS_CONFIG1_MASK GENMASK(4, 4) -#define SSD130X_SET_COM_PINS_CONFIG1_SET(val) FIELD_PREP(SSD130X_SET_COM_PINS_CONFIG1_MASK, !(val)) +#define SSD130X_SET_COM_PINS_CONFIG1_SET(val) FIELD_PREP(SSD130X_SET_COM_PINS_CONFIG1_MASK, (val)) #define SSD130X_SET_COM_PINS_CONFIG2_MASK GENMASK(5, 5) #define SSD130X_SET_COM_PINS_CONFIG2_SET(val) FIELD_PREP(SSD130X_SET_COM_PINS_CONFIG2_MASK, (val)) @@ -298,6 +298,7 @@ static void ssd130x_power_off(struct ssd130x_device *ssd130x) static int ssd130x_init(struct ssd130x_device *ssd130x) { u32 precharge, dclk, com_invdir, compins, chargepump, seg_remap; + bool scan_mode; int ret; /* Set initial contrast */ @@ -360,7 +361,13 @@ static int ssd130x_init(struct ssd130x_device *ssd130x) /* Set COM pins configuration */ compins = BIT(1); - compins |= (SSD130X_SET_COM_PINS_CONFIG1_SET(ssd130x->com_seq) | + /* + * The COM scan mode field values are the inverse of the boolean DT + * property "solomon,com-seq". The value 0b means scan from COM0 to + * COM[N - 1] while 1b means scan from COM[N - 1] to COM0. + */ + scan_mode = !ssd130x->com_seq; + compins |= (SSD130X_SET_COM_PINS_CONFIG1_SET(scan_mode) | SSD130X_SET_COM_PINS_CONFIG2_SET(ssd130x->com_lrremap)); ret = ssd130x_write_cmd(ssd130x, 2, SSD130X_SET_COM_PINS_CONFIG, compins); if (ret < 0)