linux-kernel - Re: [PATCH v2 1/2] cache: Add StarFive StarLink cache management for StarFive JH8100

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Date: Tue, 23 Apr 2024 16:54:24 +0100
From: Conor Dooley <conor@...nel.org>
To: Joshua Yeong <joshua.yeong@...rfivetech.com>
Cc: robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
	paul.walmsley@...ive.com, palmer@...belt.com, aou@...s.berkeley.edu,
	leyfoon.tan@...rfivetech.com, jeeheng.sia@...rfivetech.com,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v2 1/2] cache: Add StarFive StarLink cache management for
 StarFive JH8100

On Tue, Apr 23, 2024 at 03:26:38PM +0800, Joshua Yeong wrote:
> +
> +#include <asm/dma-noncoherent.h>
> +
> +#define STARLINK_CACHE_FLUSH_START_ADDR			0x0
> +#define STARLINK_CACHE_FLUSH_END_ADDR			0x8
> +#define STARLINK_CACHE_FLUSH_CTL			0x10
> +#define STARLINK_CACHE_CACHE_ALIGN			0x40
> +
> +#define STARLINK_CACHE_ADDRESS_RANGE_MASK		GENMASK(39, 0)
> +#define STARLINK_CACHE_FLUSH_CTL_MODE_MASK		GENMASK(2, 1)
> +#define STARLINK_CACHE_FLUSH_CTL_ENABLE_MASK		BIT(0)
> +
> +#define STARLINK_CACHE_FLUSH_CTL_CLEAN_INVALIDATE	0
> +#define STARLINK_CACHE_FLUSH_CTL_MAKE_INVALIDATE	1
> +#define STARLINK_CACHE_FLUSH_CTL_CLEAN_SHARED		2
> +#define STARLINK_CACHE_FLUSH_TIMEOUT_US			5000000
> +
> +struct starlink_cache_priv {
> +	void __iomem *base_addr;
> +};
> +
> +static struct starlink_cache_priv starlink_cache_priv;
> +
> +static void starlink_cache_flush_complete(void)
> +{
> +	volatile void __iomem *_ctl = starlink_cache_priv.base_addr +

Why does this variable have an _ prefix?

> +                                      STARLINK_CACHE_FLUSH_CTL;

This link only has spaces, it should be tabs + < 8 spaces.

> +	u64 v;
> +
> +	if (readq_poll_timeout_atomic((_ctl), v,
> +	    !(v & STARLINK_CACHE_FLUSH_CTL_ENABLE_MASK), 1,
> +	    STARLINK_CACHE_FLUSH_TIMEOUT_US))
> +		WARN(1, "StarFive Starlink cache flush operation timeout\n");
> +}

I'd fine this easier to read as:

static void starlink_cache_flush_complete(void)
{
	volatile void __iomem *_ctl = starlink_cache_priv.base_addr +
				      STARLINK_CACHE_FLUSH_CTL;
	u64 v;
	int ret;

	ret = readq_poll_timeout_atomic(_ctl, v, !(v & STARLINK_CACHE_FLUSH_CTL_ENABLE_MASK),
					STARLINK_CACHE_FLUSH_POLL_DELAY_US,
					STARLINK_CACHE_FLUSH_TIMEOUT_US);
	if (ret)
		WARN(1, "StarFive Starlink cache flush operation timeout\n");
}

Cheers,
Conor.


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