From: Wolfram Sang <wsa+renesas@sang-engineering.com>
To: Prabhakar <prabhakar.csengg@gmail.com>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
Rob Herring <robh@kernel.org>,
Krzysztof Kozlowski <krzk+dt@kernel.org>,
Conor Dooley <conor+dt@kernel.org>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Magnus Damm <magnus.damm@gmail.com>,
linux-rtc@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
Prabhakar <prabhakar.csengg+renesas@gmail.com>,
Biju Das <biju.das.jz@bp.renesas.com>,
Fabrizio Castro <fabrizio.castro.jz@renesas.com>,
Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Subject: Re: [PATCH v4 09/15] rtc: rzn1: Dynamically calculate synchronization delay based on clock rate
Date: Wed, 19 Aug 2026 15:08:21 +0200 [thread overview]
Message-ID: <aoWqxdIpvTP8zoOX@shikoro> (raw)
In-Reply-To: <20260819103926.2136712-10-prabhakar.mahadev-lad.rj@bp.renesas.com>
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On Wed, Aug 19, 2026 at 11:39:20AM +0100, Prabhakar wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
>
> Replace the hardcoded hardware synchronization delays with a calculated
> time window derived from the operating sub-clock frequency.
>
> The driver currently hardcodes microsecond ranges assuming a fixed
> sub-clock frequency of 32.768 kHz. Newer SoC variants, such as the
> RZ/T2H, drive this hardware block using a much faster clock rate
> (~195.3 kHz). Hardcoding these wait windows forces faster blocks to
> over-sleep, introducing unnecessary delays during clock initialization
> and register configuration.
>
> Calculate the duration of the required clock cycles in microseconds based
> on the runtime clock rate, and store this value in the driver private
> structure to adjust the usleep_range() and readl_poll_timeout() boundaries
> dynamically.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
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next prev parent reply other threads:[~2026-08-19 13:08 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-19 10:39 [PATCH v4 00/15] Add RTC support for Renesas RZ/T2H and RZ/N2H SoCs Prabhakar
2026-08-19 10:39 ` [PATCH v4 01/15] dt-bindings: rtc: renesas,rzn1-rtc: Add RZ/T2H and RZ/N2H support Prabhakar
2026-08-19 10:39 ` [PATCH v4 02/15] rtc: rzn1: Handle EPROBE_DEFER for optional pps interrupt Prabhakar
2026-08-19 10:39 ` [PATCH v4 03/15] rtc: rzn1: Fix weekday underflow when alarm crosses month boundary Prabhakar
2026-08-19 12:57 ` Wolfram Sang
2026-08-19 10:39 ` [PATCH v4 04/15] rtc: rzn1: Fix malformed MODULE_AUTHOR string Prabhakar
2026-08-19 10:39 ` [PATCH v4 05/15] rtc: Kconfig: Broaden RTC_DRV_RZN1 dependency to ARCH_RENESAS Prabhakar
2026-08-19 10:39 ` [PATCH v4 06/15] rtc: rzn1: Fix alarm range check truncation on 32-bit systems Prabhakar
2026-08-19 10:39 ` [PATCH v4 07/15] rtc: rzn1: Replace remove callback with devm_add_action_or_reset() Prabhakar
2026-08-19 10:39 ` [PATCH v4 08/15] rtc: rzn1: Use pm_runtime_put_sync() in rzn1_rtc_disable_hardware() Prabhakar
2026-08-19 10:39 ` [PATCH v4 09/15] rtc: rzn1: Dynamically calculate synchronization delay based on clock rate Prabhakar
2026-08-19 13:08 ` Wolfram Sang [this message]
2026-08-19 10:39 ` [PATCH v4 10/15] rtc: rzn1: Use temporary variable for struct device Prabhakar
2026-08-19 10:39 ` [PATCH v4 11/15] rtc: rzn1: Consistently use dev_err_probe() Prabhakar
2026-08-19 10:39 ` [PATCH v4 12/15] rtc: rzn1: use FIELD_PREP/FIELD_GET and GENMASK for register access Prabhakar
2026-08-19 10:39 ` [PATCH v4 13/15] rtc: rzn1: Add OF match data to gate SUBU " Prabhakar
2026-08-19 13:12 ` Wolfram Sang
2026-08-19 10:39 ` [PATCH v4 14/15] rtc: rzn1: Drop trailing comma from OF match table sentinel Prabhakar
2026-08-19 13:13 ` Wolfram Sang
2026-08-19 10:39 ` [PATCH v4 15/15] rtc: rzn1: Add support for Renesas RZ/T2H and RZ/N2H SoCs Prabhakar
2026-08-19 13:14 ` Wolfram Sang
2026-08-19 13:15 ` [PATCH v4 00/15] Add RTC " Wolfram Sang
2026-08-19 19:46 ` Wolfram Sang
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