From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Viorel Suman <viorel.suman@nxp.com>
Cc: "Viorel Suman (OSS)" <viorel.suman@oss.nxp.com>,
Florin Leotescu <florin.leotescu@nxp.com>,
Shawn Guo <shawnguo@kernel.org>,
Sascha Hauer <s.hauer@pengutronix.de>,
Pengutronix Kernel Team <kernel@pengutronix.de>,
Fabio Estevam <festevam@gmail.com>,
NXP Linux Team <linux-imx@nxp.com>,
linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] pwm: imx-tpm: reset module on probe
Date: Thu, 15 Feb 2024 11:12:30 +0100 [thread overview]
Message-ID: <zeieriiouilwf23g4v5wv7oetdee43qcm5lvxiygyxmxm7lgde@m3a2uain6g45> (raw)
In-Reply-To: <3d866664-d2fd-4d36-9e8f-5242327e41b9@nxp.com>
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Hello,
On Thu, Feb 01, 2024 at 06:25:26PM +0200, Viorel Suman wrote:
> On 2/1/24 15:38, Uwe Kleine-König wrote:
> > > + /* Resets all internal logic and registers */
> > > + writel(PWM_IMX_TPM_GLOBAL_RST, tpm->base + PWM_IMX_TPM_GLOBAL);
> > > + writel(0, tpm->base + PWM_IMX_TPM_GLOBAL);
> > > +
> > This opposes the use case that the bootloader setup the pwm-backlight to
> > show a splash screen that is simply taken over by Linux without
> > flickering, right?
>
> Yes, I was not aware of such use case. Is it acceptable if I'll update
>
> the patch in a such way so that the software reset happens as function
>
> of a property in the related DTS node ?
That sounds wrong. Why do you reset at all? If at all, only reset if all
channels are disabled (if at all).
> > Otherwise the commit log should motivate why "the module takes the
> > default state" is better than the status quo and what this default state
> > is.
>
> The default state above means IP internal logic being reset to the initial
> state and
>
> registers values being set to their reset values. We're facing a situation
> on iMX95 when
>
> A core may be reset independently from the rest of the SoC, this triggers a
> new
>
> SPL->U-Boot->Linux boot, and in Linux probe phase PWM will inherit its state
> from
>
> previous Linux runtime - this leads to some issues in suspend/resume
> functionality.
What kind of issues?
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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prev parent reply other threads:[~2024-02-15 10:12 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-01 12:22 [PATCH] pwm: imx-tpm: reset module on probe Viorel Suman (OSS)
2024-02-01 13:38 ` Uwe Kleine-König
[not found] ` <3d866664-d2fd-4d36-9e8f-5242327e41b9@nxp.com>
2024-02-15 10:12 ` Uwe Kleine-König [this message]
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