Re: [PATCH v2] phy: mediatek: rework the floating point comparisons to fixed point

From: "Chunfeng Yun (云春峰)" <Chunfeng.Yun@mediatek.com>
To: "p.zabel@pengutronix.de" <p.zabel@pengutronix.de>,
	"matthias.bgg@gmail.com" <matthias.bgg@gmail.com>,
	"vkoul@kernel.org" <vkoul@kernel.org>,
	"trix@redhat.com" <trix@redhat.com>,
	"chunkuang.hu@kernel.org" <chunkuang.hu@kernel.org>,
	"kishon@kernel.org" <kishon@kernel.org>,
	"angelogioacchino.delregno@collabora.com"
	<angelogioacchino.delregno@collabora.com>
Cc: "dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-mediatek@lists.infradead.org"
	<linux-mediatek@lists.infradead.org>,
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Subject: Re: [PATCH v2] phy: mediatek: rework the floating point comparisons to fixed point
Date: Thu, 4 May 2023 07:53:33 +0000	[thread overview]
Message-ID: <f48580115b4fddf07a1dfabaf240a17d8d712ce9.camel@mediatek.com> (raw)
In-Reply-To: <20230502145005.2927101-1-trix@redhat.com>

On Tue, 2023-05-02 at 10:50 -0400, Tom Rix wrote:
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
> 
> 
> gcc on aarch64 reports
> drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c: In function
> ‘mtk_hdmi_pll_set_rate’:
> drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c:240:52: error: ‘-mgeneral-
> regs-only’
>   is incompatible with the use of floating-point types
>   240 |         else if (tmds_clk >= 54 * MEGA && tmds_clk < 148.35 *
> MEGA)
> 
> Floating point should not be used, so rework the floating point
> comparisons
> to fixed point.
> 
> Signed-off-by: Tom Rix <trix@redhat.com>
> ---
> v2: silence robot by casting types to u64
> 
> ---
> drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c
> b/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c
> index abfc077fb0a8..093c4d1da557 100644
> --- a/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c
> +++ b/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c
> @@ -237,11 +237,11 @@ static int mtk_hdmi_pll_calc(struct
> mtk_hdmi_phy *hdmi_phy, struct clk_hw *hw,
>          */
>         if (tmds_clk < 54 * MEGA)
>                 txposdiv = 8;
> -       else if (tmds_clk >= 54 * MEGA && tmds_clk < 148.35 * MEGA)
> +       else if (tmds_clk >= 54 * MEGA && (tmds_clk * 100) < 14835 *
> MEGA)
>                 txposdiv = 4;
> -       else if (tmds_clk >= 148.35 * MEGA && tmds_clk < 296.7 *
> MEGA)
> +       else if ((tmds_clk * 100) >= 14835 * MEGA && (tmds_clk * 10)
> < 2967 * MEGA)
>                 txposdiv = 2;
> -       else if (tmds_clk >= 296.7 * MEGA && tmds_clk <= 594 * MEGA)
> +       else if ((tmds_clk * 10) >= 2967 * MEGA && tmds_clk <= 594 *
> MEGA)
>                 txposdiv = 1;
>         else
>                 return -EINVAL;
> @@ -328,12 +328,12 @@ static int mtk_hdmi_pll_drv_setting(struct
> clk_hw *hw)
>                 clk_channel_bias = 0x34; /* 20mA */
>                 impedance_en = 0xf;
>                 impedance = 0x36; /* 100ohm */
> -       } else if (pixel_clk >= 74.175 * MEGA && pixel_clk <= 300 *
> MEGA) {
> +       } else if (((u64)pixel_clk * 1000) >= 74175 * MEGA &&
> pixel_clk <= 300 * MEGA) {
>                 data_channel_bias = 0x34; /* 20mA */
>                 clk_channel_bias = 0x2c; /* 16mA */
>                 impedance_en = 0xf;
>                 impedance = 0x36; /* 100ohm */
> -       } else if (pixel_clk >= 27 * MEGA && pixel_clk < 74.175 *
> MEGA) {
> +       } else if (pixel_clk >= 27 * MEGA && ((u64)pixel_clk * 1000)
> < 74175 * MEGA) {
>                 data_channel_bias = 0x14; /* 10mA */
>                 clk_channel_bias = 0x14; /* 10mA */
>                 impedance_en = 0x0;
> --
> 2.27.0

Reviewed-by: Chunfeng Yun <chunfeng.yun@mediatek.com>

Thanks
>