linux-kernel - Re: [PATCH 4/6] PCI/VGA: Move the new

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Date:   Mon, 24 Jul 2023 21:02:14 +0800
From:   suijingfeng <suijingfeng@...ngson.cn>
To:     Sui Jingfeng <sui.jingfeng@...ux.dev>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        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>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, loongson-kernel@...ts.loongnix.cn
Subject: Re: [PATCH 4/6] PCI/VGA: Move the new_state assignment out the loop

PING, please !


On 2023/7/11 21:43, Sui Jingfeng wrote:
> From: Sui Jingfeng <suijingfeng@...ngson.cn>
>
> In the vga_arbiter_notify_clients() function, the value of the 'new_state'
> variable will be 'false' on systems that have more than one PCI VGA card.
> Its value will be 'true' on systems that have one or no PCI VGA compatible
> card. In other words, its value is not relevant to the iteration, so move
> the assignment () out of the loop.
>
> For a system with multiple video cards, this patch saves the redundant
> assignment.
>
> Signed-off-by: Sui Jingfeng <suijingfeng@...ngson.cn>
> ---
>   drivers/pci/vgaarb.c | 16 +++++++---------
>   1 file changed, 7 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
> index 668139f7c247..4c448c758bab 100644
> --- a/drivers/pci/vgaarb.c
> +++ b/drivers/pci/vgaarb.c
> @@ -1468,22 +1468,20 @@ static void vga_arbiter_notify_clients(void)
>   {
>   	struct vga_device *vgadev;
>   	unsigned long flags;
> -	uint32_t new_decodes;
> -	bool new_state;
> +	bool state;
>   
>   	if (!vga_arbiter_used)
>   		return;
>   
> +	state = (vga_count > 1) ? false : true;
> +
>   	spin_lock_irqsave(&vga_lock, flags);
>   	list_for_each_entry(vgadev, &vga_list, list) {
> -		if (vga_count > 1)
> -			new_state = false;
> -		else
> -			new_state = true;
>   		if (vgadev->set_decode) {
> -			new_decodes = vgadev->set_decode(vgadev->pdev,
> -							 new_state);
> -			vga_update_device_decodes(vgadev, new_decodes);
> +			unsigned int decodes;
> +
> +			decodes = vgadev->set_decode(vgadev->pdev, state);
> +			vga_update_device_decodes(vgadev, decodes);
>   		}
>   	}
>   	spin_unlock_irqrestore(&vga_lock, flags);