linux-kernel - Re: [PATCH v10 07/11] drm/etnaviv: Add support for the dma coherent device

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Message-ID: <aa73348d-5ec8-4ac0-2ec0-0cce24756c63@loongson.cn>
Date:   Wed, 21 Jun 2023 22:44:54 +0800
From:   Sui Jingfeng <suijingfeng@...ngson.cn>
To:     Lucas Stach <l.stach@...gutronix.de>,
        Sui Jingfeng <18949883232@....com>,
        Russell King <linux+etnaviv@...linux.org.uk>,
        Christian Gmeiner <christian.gmeiner@...il.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        etnaviv@...ts.freedesktop.org,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH v10 07/11] drm/etnaviv: Add support for the dma coherent
 device

Hi,

On 2023/6/21 18:00, Lucas Stach wrote:
>> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.h b/drivers/gpu/drm/etnaviv/etnaviv_drv.h
>> index 9cd72948cfad..644e5712c050 100644
>> --- a/drivers/gpu/drm/etnaviv/etnaviv_drv.h
>> +++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.h
>> @@ -46,6 +46,12 @@ struct etnaviv_drm_private {
>>   	struct xarray active_contexts;
>>   	u32 next_context_id;
>>   
>> +	/*
>> +	 * If true, the GPU is capable of snooping cpu cache. Here, it
>> +	 * also means that cache coherency is enforced by the hardware.
>> +	 */
>> +	bool dma_coherent;
>> +
> No need for this, I think. Just use dev_is_dma_coherent() where you
> need to know this.
>
No, we want this value cached by the driver.

We only need call  dev_is_dma_coherent() once!

We need to reuse this variable on other places.

-- 
Jingfeng