linux-kernel - Re: [PATCH v14 1/2] drm: add kms driver for loongson display controller

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Message-ID: <47bfa5a1-8a60-6faa-1983-d8a29589cdb6@189.cn>
Date:   Mon, 22 May 2023 17:05:10 +0800
From:   Sui Jingfeng <15330273260@....cn>
To:     WANG Xuerui <kernel@...0n.name>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Sui Jingfeng <suijingfeng@...ngson.cn>,
        Li Yi <liyi@...ngson.cn>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian Koenig <christian.koenig@....com>,
        Emil Velikov <emil.l.velikov@...il.com>
Cc:     linaro-mm-sig@...ts.linaro.org, loongson-kernel@...ts.loongnix.cn,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Javier Martinez Canillas <javierm@...hat.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Liu Peibao <liupeibao@...ngson.cn>, linux-media@...r.kernel.org
Subject: Re: [PATCH v14 1/2] drm: add kms driver for loongson display
 controller

Hi,

On 2023/5/21 20:21, WANG Xuerui wrote:
>> +++ b/drivers/gpu/drm/loongson/lsdc_debugfs.c
>> @@ -0,0 +1,91 @@
>> +// SPDX-License-Identifier: GPL-2.0+
>> +/*
>> + * Copyright (C) 2023 Loongson Technology Corporation Limited
>> + */
>> +
>> +#include <drm/drm_debugfs.h>
>> +
>> +#include "lsdc_benchmark.h"
>> +#include "lsdc_drv.h"
>> +#include "lsdc_gem.h"
>> +#include "lsdc_probe.h"
>> +#include "lsdc_ttm.h"
>> +
>> +/* device level debugfs */
>> +
>> +static int lsdc_identify(struct seq_file *m, void *arg)
>> +{
>> +    struct drm_info_node *node = (struct drm_info_node *)m->private;
>> +    struct lsdc_device *ldev = (struct lsdc_device 
>> *)node->info_ent->data;
>> +    const struct loongson_gfx_desc *gfx = to_loongson_gfx(ldev->descp);
>> +    u8 impl, rev;
>> +
>> +    loongson_cpu_get_prid(&impl, &rev);
>> +
>> +    seq_printf(m, "Running on cpu 0x%x, cpu revision: 0x%x\n",
>> +           impl, rev);
>
> Is this really needed/relevant for LSDC identification? AFAICS the 
> loongson_cpu_get_prid helper has only one use (that's here), 

Yes, this is really needed, when doing the remote debugging, sometime 
you only have a ssh login the target machine.

User of the driver could know what the host is in the DRM way.

> so if it's not absolutely necessary you can just get rid of that 
> function and lsdc_probe.h altogether.
This function it written for the future, It will not be removed.
>
>> +
>> +    seq_printf(m, "Contained in: %s\n", gfx->model);
>
> "model: " would be more appropriate for a piece of info looking like a 
> "gfx->model"?
No, these are nearly equivalent.