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Date: Tue, 7 May 2024 17:01:00 +0300
From: Andy Shevchenko <andriy.shevchenko@intel.com>
To: Ilpo =?iso-8859-1?Q?J=E4rvinen?= <ilpo.jarvinen@linux.intel.com>,
	Yury Norov <yury.norov@gmail.com>
Cc: linux-pci@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Rob Herring <robh@kernel.org>,
	Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
	Igor Mammedov <imammedo@redhat.com>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 7/8] PCI: Make minimum bridge window alignment
 reference more obvious
Message-ID: <Zjo0HJDBVr-FPFfn@smile.fi.intel.com>
References: <20240507102523.57320-1-ilpo.jarvinen@linux.intel.com>
 <20240507102523.57320-8-ilpo.jarvinen@linux.intel.com>
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Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo

On Tue, May 07, 2024 at 01:25:22PM +0300, Ilpo J?rvinen wrote:
> Calculations related to bridge window size contain literal 20 that is
> the minimum alignment for a bridge window. Make the code more obvious
> by converting the literal 20 to __ffs(SZ_1MB).

..

> -		align1 <<= (order + 20);
> +		align1 <<= (order + __ffs(SZ_1M));

No need for outer parentheses.

..

> +			order = __ffs(align) - __ffs(SZ_1M);

Yeah, would be nice to have something like

#define bit_distance(a, b)	(ffs(a) - fls(b))

in bitops.h as we have a few users and I have heard about one more coming,
but this is topic to another discussion. (Yuri, just FYI.)

-- 
With Best Regards,
Andy Shevchenko