Linux PWM subsystem development
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From: "Uwe Kleine-König" <ukleinek@kernel.org>
To: "Ola Chr. Vaage" <o.c.vage@gmail.com>
Cc: Thierry Reding <thierry.reding@kernel.org>,
	 Jonathan Hunter <jonathanh@nvidia.com>,
	linux-pwm@vger.kernel.org, linux-tegra@vger.kernel.org,
	 linux-kernel@vger.kernel.org,
	"Ola Chr. Vaage" <ola.christoffer.vage@scoutdi.com>
Subject: Re: [PATCH] pwm: tegra: fix doubled output frequency due to divider truncation
Date: Tue, 14 Jul 2026 14:08:33 +0200	[thread overview]
Message-ID: <alYmY0535HVPRNz2@monoceros> (raw)
In-Reply-To: <alX5fmfHs1CW_bps@monoceros>

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Hello again,

On Tue, Jul 14, 2026 at 11:14:58AM +0200, Uwe Kleine-König wrote:
> The usual behaviour for .apply() is to pick the largest possible period
> not larger than the requested period (and similar for duty_cycle). The
> tegra PWM driver doesn't do that and instead trys to pick a nearest
> match. If you change how the configuration happens, the only acceptable
> way is to migrate to the usual behaviour, still better, convert to the
> waveform callbacks.
> 
> The driver also lacks a .get_state() callback and should not use
> pwm_is_enabled(). Also calling tegra_pwm_config() discards bits from
> state->duty_cycle and state->period if they are bigger than INT_MAX.
> 
> So there are some things to work on in that driver, but don't make the
> clock selection not more complicated as it already is and as is
> necessary.

I started on that, but failed to Cc: you. Please see
https://lore.kernel.org/linux-pwm/cover.1784030076.git.ukleinek@kernel.org

Best regards
Uwe

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      reply	other threads:[~2026-07-14 12:08 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-13 11:15 [PATCH] pwm: tegra: fix doubled output frequency due to divider truncation Ola Chr. Vaage
2026-07-14  9:14 ` Uwe Kleine-König
2026-07-14 12:08   ` Uwe Kleine-König [this message]

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