linux-kernel - Re: [PATCH 5/9] drm/meson: dw-hdmi: split resets out of hw init.

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]

Message-ID: <8d49f427-a0f8-44f4-bd46-86fbf385deab@linaro.org>
Date: Mon, 19 Aug 2024 18:08:34 +0200
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Jerome Brunet <jbrunet@...libre.com>,
 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: Kevin Hilman <khilman@...libre.com>,
 Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
 dri-devel@...ts.freedesktop.org, linux-amlogic@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/9] drm/meson: dw-hdmi: split resets out of hw init.

On 30/07/2024 14:50, Jerome Brunet wrote:
> This prepares the migration to regmap usage.
> 
> To properly setup regmap, the APB needs to be in working order.
> This is easier handled if the resets are not mixed with hw init.
> 
> More checks are required to determine if the resets are needed
> on resume or not. Add a note for this.
> 
> Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
> ---
>   drivers/gpu/drm/meson/meson_dw_hdmi.c | 14 +++++++++-----
>   1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> index 5cd3264ab874..47aa3e184e98 100644
> --- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
> +++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> @@ -581,11 +581,6 @@ static void meson_dw_hdmi_init(struct meson_dw_hdmi *meson_dw_hdmi)
>   	/* Bring HDMITX MEM output of power down */
>   	regmap_update_bits(priv->hhi, HHI_MEM_PD_REG0, 0xff << 8, 0);
>   
> -	/* Reset HDMITX APB & TX & PHY */
> -	reset_control_reset(meson_dw_hdmi->hdmitx_apb);
> -	reset_control_reset(meson_dw_hdmi->hdmitx_ctrl);
> -	reset_control_reset(meson_dw_hdmi->hdmitx_phy);
> -
>   	/* Enable APB3 fail on error */
>   	if (!meson_vpu_is_compatible(priv, VPU_COMPATIBLE_G12A)) {
>   		writel_bits_relaxed(BIT(15), BIT(15),
> @@ -675,6 +670,10 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
>   		return PTR_ERR(meson_dw_hdmi->hdmitx_phy);
>   	}
>   
> +	reset_control_reset(meson_dw_hdmi->hdmitx_apb);
> +	reset_control_reset(meson_dw_hdmi->hdmitx_ctrl);
> +	reset_control_reset(meson_dw_hdmi->hdmitx_phy);
> +
>   	meson_dw_hdmi->hdmitx = devm_platform_ioremap_resource(pdev, 0);
>   	if (IS_ERR(meson_dw_hdmi->hdmitx))
>   		return PTR_ERR(meson_dw_hdmi->hdmitx);
> @@ -765,6 +764,11 @@ static int __maybe_unused meson_dw_hdmi_pm_resume(struct device *dev)
>   	if (!meson_dw_hdmi)
>   		return 0;
>   
> +	/* TODO: Is this really necessary/desirable on resume ? */

Yes to reset the HDMI controller to it's default state, not sure if the note is important here.

> +	reset_control_reset(meson_dw_hdmi->hdmitx_apb);
> +	reset_control_reset(meson_dw_hdmi->hdmitx_ctrl);
> +	reset_control_reset(meson_dw_hdmi->hdmitx_phy);
> +
>   	meson_dw_hdmi_init(meson_dw_hdmi);
>   
>   	dw_hdmi_resume(meson_dw_hdmi->hdmi);