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From: Stephen Boyd <sboyd@codeaurora.org>
To: Colin Cross <ccross@android.com>
Cc: linux-tegra@vger.kernel.org,
	Russell King <linux@arm.linux.org.uk>,
	konkers@android.com, linux-kernel@vger.kernel.org,
	olof@lixom.net, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 12/21] ARM: tegra: clock: Add shared bus clock type
Date: Wed, 16 Feb 2011 12:34:40 -0800	[thread overview]
Message-ID: <4D5C34E0.5000209@codeaurora.org> (raw)
In-Reply-To: <1297590033-15035-13-git-send-email-ccross@android.com>

On 02/13/2011 01:40 AM, Colin Cross wrote:
> +/* shared bus ops */
> +/*
> + * Some clocks may have multiple downstream users that need to request a
> + * higher clock rate.  Shared bus clocks provide a unique shared_bus_user
> + * clock to each user.  The frequency of the bus is set to the highest
> + * enabled shared_bus_user clock, with a minimum value set by the
> + * shared bus.
> + */
> +static void tegra_clk_shared_bus_update(struct clk *bus)
> +{
> +	struct clk *c;
> +	unsigned long rate = bus->min_rate;
> +
> +	list_for_each_entry(c, &bus->shared_bus_list, u.shared_bus_user.node)
> +		if (c->u.shared_bus_user.enabled)
> +			rate = max(c->u.shared_bus_user.rate, rate);
> +
> +	if (rate != clk_get_rate(bus))
> +		clk_set_rate(bus, rate);

What do you do if clk_set_rate() fails? Should you unwind all the state
such as the rate and if it's enabled/disabled? Or is it safe to say
clk_set_rate() can't fail unless the kernel is buggy in which case why
aren't all those return -E* in the set rate functions just BUG_ONs?

> +};
> +
> +static void tegra_clk_shared_bus_init(struct clk *c)
> +{
> +	c->max_rate = c->parent->max_rate;
> +	c->u.shared_bus_user.rate = c->parent->max_rate;
> +	c->state = OFF;
> +#ifdef CONFIG_DEBUG_FS
> +	c->set = 1;
> +#endif
> +
> +	list_add_tail(&c->u.shared_bus_user.node,
> +		&c->parent->shared_bus_list);
> +}
> +
> +static int tegra_clk_shared_bus_set_rate(struct clk *c, unsigned long rate)
> +{
> +	c->u.shared_bus_user.rate = rate;
> +	tegra_clk_shared_bus_update(c->parent);
> +	return 0;
> +}
> +
> +static long tegra_clk_shared_bus_round_rate(struct clk *c, unsigned long rate)
> +{
> +	return clk_round_rate(c->parent, rate);
> +}
> +
> +static int tegra_clk_shared_bus_enable(struct clk *c)
> +{
> +	c->u.shared_bus_user.enabled = true;
> +	tegra_clk_shared_bus_update(c->parent);
> +	return 0;
> +}

Shouldn't you call clk_enable(c->parent)? And do you need to check for
errors from clk_enable()?

> +
> +static void tegra_clk_shared_bus_disable(struct clk *c)
> +{
> +	c->u.shared_bus_user.enabled = false;
> +	tegra_clk_shared_bus_update(c->parent);
> +}

And a similar clk_disable(c->parent) here.

-- 
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.


  reply	other threads:[~2011-02-16 20:34 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1297590033-15035-1-git-send-email-ccross@android.com>
2011-02-13  9:40 ` [PATCH 01/21] ARM: tegra: clock: enable clk reset for non-peripheral clocks Colin Cross
2011-02-13  9:40 ` [PATCH 02/21] ARM: tegra: clock: Don't BUG on changing an enabled PLL Colin Cross
2011-02-13  9:40 ` [PATCH 03/21] ARM: tegra: clock: Drop debugging Colin Cross
2011-02-13  9:40 ` [PATCH 04/21] ARM: tegra: clock: Don't use PLL lock bits Colin Cross
2011-02-13  9:40 ` [PATCH 05/21] ARM: tegra: clock: Disable clocks left on by bootloader Colin Cross
2011-02-13  9:40 ` [PATCH 06/21] ARM: tegra: clock: Initialize clocks that have no enable Colin Cross
2011-02-13  9:40 ` [PATCH 07/21] ARM: tegra: clock: Drop CPU dvfs Colin Cross
2011-02-13  9:40 ` [PATCH 08/21] ARM: tegra: clock: Rearrange static clock tables Colin Cross
2011-02-13  9:40 ` [PATCH 09/21] ARM: tegra: clock: Move unshared clk struct members into union Colin Cross
2011-02-13  9:40 ` [PATCH 10/21] ARM: tegra: clock: Convert global lock to a lock per clock Colin Cross
2011-02-13  9:40 ` [PATCH 11/21] ARM: tegra: cpufreq: Take an extra reference to pllx Colin Cross
2011-02-13  9:40 ` [PATCH 12/21] ARM: tegra: clock: Add shared bus clock type Colin Cross
2011-02-16 20:34   ` Stephen Boyd [this message]
2011-02-16 21:01     ` Colin Cross
2011-02-16 21:51       ` Stephen Boyd
2011-02-16 22:03         ` Colin Cross
2011-02-13  9:40 ` [PATCH 13/21] ARM: tegra: clock: Remove unnecessary uses of #ifdef CONFIG_DEBUG_FS Colin Cross
2011-02-13  9:40 ` [PATCH 14/21] ARM: tegra: clock: Refcount periph clock enables Colin Cross
2011-02-13  9:40 ` [PATCH 15/21] ARM: tegra: clock: Round rate before setting rate Colin Cross
2011-02-13  9:40 ` [PATCH 16/21] ARM: tegra: Add external memory controller driver Colin Cross
2011-02-13  9:40 ` [PATCH 17/21] ARM: tegra: clocks: Add emc scaling Colin Cross
2011-02-13  9:40 ` [PATCH 18/21] ARM: tegra: cpufreq: Adjust memory frequency with cpu frequency Colin Cross
2011-02-13  9:40 ` [PATCH 19/21] ARM: tegra: clock: Add function to set SDMMC tap delay Colin Cross
2011-02-13  9:40 ` [PATCH 20/21] ARM: tegra: clock: Fix clock issues in suspend Colin Cross
2011-02-13  9:40 ` [PATCH 21/21] ARM: tegra: clock: Miscellaneous clock updates Colin Cross

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