linux-kernel - Re: [PATCH v2] drm/msm/dsi: Add parentheses to quirks check in dsi_phy_hw_v3_0_lane

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Message-ID: <20190619193237.GG25413@art_vandelay>
Date:   Wed, 19 Jun 2019 15:32:37 -0400
From:   Sean Paul <sean@...rly.run>
To:     Nathan Chancellor <natechancellor@...il.com>
Cc:     Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com,
        kbuild test robot <lkp@...el.com>,
        Jeffrey Hugo <jeffrey.l.hugo@...il.com>
Subject: Re: [PATCH v2] drm/msm/dsi: Add parentheses to quirks check in
 dsi_phy_hw_v3_0_lane_settings

On Wed, Jun 19, 2019 at 12:17:23PM -0700, Nathan Chancellor wrote:
> Clang warns:
> 
> drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c:80:6: warning: logical not is
> only applied to the left hand side of this bitwise operator
> [-Wlogical-not-parentheses]
>         if (!phy->cfg->quirks & V3_0_0_10NM_OLD_TIMINGS_QUIRK) {
>             ^                 ~
> drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c:80:6: note: add parentheses
> after the '!' to evaluate the bitwise operator first
>         if (!phy->cfg->quirks & V3_0_0_10NM_OLD_TIMINGS_QUIRK) {
>             ^
>              (                                               )
> drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c:80:6: note: add parentheses
> around left hand side expression to silence this warning
>         if (!phy->cfg->quirks & V3_0_0_10NM_OLD_TIMINGS_QUIRK) {
>             ^
>             (                )
> 1 warning generated.
> 
> Add parentheses around the bitwise AND so it is evaluated first then
> negated.
> 
> Fixes: 3dbbf8f09e83 ("drm/msm/dsi: Add old timings quirk for 10nm phy")

Hmm, so it looks like this patch isn't upstream. What tree are you basing this
on?

Sean

> Link: https://github.com/ClangBuiltLinux/linux/issues/547
> Reported-by: kbuild test robot <lkp@...el.com>
> Reviewed-by: Jeffrey Hugo <jeffrey.l.hugo@...il.com>
> Reviewed-by: Sean Paul <sean@...rly.run>
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
> ---
> 
> v1 -> v2:
> 
> * Fix broken link (thanks to Sean for pointing it out)
> * Add Sean's reviewed-by
> 
>  drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c
> index eb28937f4b34..47403d4f2d28 100644
> --- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c
> +++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c
> @@ -77,7 +77,7 @@ static void dsi_phy_hw_v3_0_lane_settings(struct msm_dsi_phy *phy)
>  			      tx_dctrl[i]);
>  	}
>  
> -	if (!phy->cfg->quirks & V3_0_0_10NM_OLD_TIMINGS_QUIRK) {
> +	if (!(phy->cfg->quirks & V3_0_0_10NM_OLD_TIMINGS_QUIRK)) {
>  		/* Toggle BIT 0 to release freeze I/0 */
>  		dsi_phy_write(lane_base + REG_DSI_10nm_PHY_LN_TX_DCTRL(3), 0x05);
>  		dsi_phy_write(lane_base + REG_DSI_10nm_PHY_LN_TX_DCTRL(3), 0x04);
> -- 
> 2.22.0
> 

-- 
Sean Paul, Software Engineer, Google / Chromium OS