linux-kernel - Re: [PATCH 4/4] spi: bcm-mspi: Add support to set serial baud clock rate

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]

Date:	Sat, 04 Apr 2015 12:12:59 -0700
From:	Florian Fainelli <f.fainelli@...il.com>
To:	Jonathan Richardson <jonathar@...adcom.com>,
	Mark Brown <broonie@...nel.org>,
	Dmitry Torokhov <dtor@...gle.com>,
	Anatol Pomazau <anatol@...gle.com>
CC:	Scott Branden <sbranden@...adcom.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	linux-kernel@...r.kernel.org, linux-spi@...r.kernel.org,
	bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>,
	devicetree@...r.kernel.org, Rafal Milecki <zajec5@...il.com>,
	Brian Norris <computersforpeace@...il.com>,
	Kevin Cernekee <cernekee@...il.com>
Subject: Re: [PATCH 4/4] spi: bcm-mspi: Add support to set serial baud clock
 rate

Le 02/04/2015 12:23, Jonathan Richardson a écrit :
> The driver wasn't setting the SPBR (serial clock baud rate) which caused
> it to run at the slowest speed possible. The driver now calculates the
> SPBR based on the reference clock frequency resulting in much faster
> SPI transfers.
> 
> Signed-off-by: Jonathan Richardson <jonathar@...adcom.com>
> ---

[snip]

> +	data->clk = devm_clk_get(dev, "mspi_clk");
> +	if (!IS_ERR(data->clk)) {
> +		int ret = clk_prepare_enable(data->clk);
> +
> +		if (ret < 0) {
> +			dev_err(dev, "failed to enable clock: %d\n", ret);
> +			return 0;
> +		}
> +
> +		/* Calculate SPBR if clock-frequency provided. */
> +		if (of_property_read_u32(dev->of_node, "clock-frequency",
> +			&desired_rate) >= 0) {
> +			u32 spbr = clk_get_rate(data->clk) / (2 * desired_rate);

Usually, specifying a "clock-frequency" property is done when there is
no clock provider available, yet we take this code path only if we could
find a "mspi_clk" which sounds a litle weird.

Once there is a proper "mspi_clk" clock, I would make it mandatory for
the clock provider to be able to provide the rate as well?
--
Florian
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/