Re: [PATCH v2 0/3] clk: meson: rounding for fast clocks on 32-bit SoCs
From: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Date: 2021-06-22 21:05:10
Also in:
linux-amlogic, linux-clk, lkml
Hi Stephen, On Mon, Jun 7, 2021 at 9:04 AM Jerome Brunet [off-list ref] wrote:
On Fri 04 Jun 2021 at 19:18, Martin Blumenstingl [off-list ref] wrote:quoted
Hi Jerome, Hi Stephen, On Mon, May 24, 2021 at 12:37 PM Martin Blumenstingl [off-list ref] wrote:quoted
On the 32-bit Amlogic Meson8/8b/8m2 SoCs we run into a problem with the fast HDMI PLL and it's OD (post-dividers). This clock tree can run at up to approx. 3GHz. This however causes a problem, because these rates require BIT(31) to be usable. Unfortunately this is not the case with clk_ops.round_rate on 32-bit systems. BIT(31) is reserved for the sign (+ or -). clk_ops.determine_rate does not suffer from this limitation. It uses an int to signal any errors and can then take all availble 32 bits for the clock rate. Changes since v1 from [0]: - reworked the first patch so the the existing divider_{ro_}round_rate_parent implementations are using the new divider_{ro_}determine_rate implementations to avoid code duplication (thanks Jerome for the suggestion) - added a patch to switch the default clk_divider_{ro_}ops to use .determine_rate instead of .round_rate as suggested by Jerome (thanks) - dropped a patch for the Meson PLL ops as these are independent from the divider patches and Jerome has applied that one directly (thanks) - added Jerome's Reviewed-by to the meson clk-regmap patch (thanks!) - dropped the RFC prefixplease let me know what you think about this v2 I am asking because clk-divider is widely used, so I'd appreciate if this gets some time in linux-next (so for example Kernel CI can test this and report issues if there are any).
Do you have any comments on this series? I am fine with it skipping 5.14 as it's a change which affects multiple platforms. So I would like to use the time until the trees are opening for patches targeting 5.15 to iron out code-review comments.
Looks good to me Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>
Thanks Jerome - I'll add it to v3 once I send it (assuming nothing major changes) Best regards, Martin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel