linux-kernel - Re: [PATCH] LoongArch: Update the flush cache policy

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Message-ID: <cbb24599-8b40-cd27-6ce7-215476c0ddf4@kylinos.cn>
Date: Mon, 6 May 2024 18:08:10 +0800
From: lijun <lijun01@...inos.cn>
To: Xi Ruoyao <xry111@...111.site>, chenhuacai@...nel.org, kernel@...0n.name,
 lvjianmin@...ngson.cn, dongbiao@...ngson.cn, zhangbaoqi@...ngson.cn
Cc: loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] LoongArch: Update the flush cache policy

volatile prevents compiler optimization by allowing the compiler

  to reread the address value of addr every time

在 2024/5/6 17:28, Xi Ruoyao 写道:
> On Mon, 2024-05-06 at 17:24 +0800, Li Jun wrote:
>> fix when LoongArch s3 resume, Can't find image information
>>
>> Signed-off-by: Li Jun <lijun01@...inos.cn>
>> Signed-off-by: Baoqi Zhang <zhangbaoqi@...ngson.cn>
>> Signed-off-by: Jianmin Lv <lvjianmin@...ngson.cn>
>> Signed-off-by: Biao Dong <dongbiao@...ngson.cn>
>> ---
>>   arch/loongarch/mm/cache.c | 24 +++++++++++++++++++++++-
>>   1 file changed, 23 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/loongarch/mm/cache.c b/arch/loongarch/mm/cache.c
>> index 6be04d36ca07..52872fa0e5d8 100644
>> --- a/arch/loongarch/mm/cache.c
>> +++ b/arch/loongarch/mm/cache.c
>> @@ -63,6 +63,28 @@ static void flush_cache_leaf(unsigned int leaf)
>>   	} while (--nr_nodes > 0);
>>   }
>>   
>> +static void flush_cache_last_level(unsigned int leaf)
>> +{
>> +	u64 addr;
>> +	int i, j, nr_nodes, way_size;
>> +	struct cache_desc *cdesc = current_cpu_data.cache_leaves +
>> leaf;
>> +
>> +	nr_nodes = loongson_sysconf.nr_nodes;
>> +
>> +	addr = CSR_DMW1_BASE;
>> +	iocsr_write32(0x1, 0x280);
>> +	way_size = cdesc->sets * cdesc->linesz;
>> +	do {
>> +		for (i = 0; i < (cdesc->ways * 3); i++) {
>> +			for (j = 0; j < (cdesc->sets); j++) {
>> +				*(volatile u32 *)addr;
> ??? what does this line do?
>