linux-kernel - Re: [PATCH] tty/nozomi: use pci_iomap instead of ioremap

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Message-ID: <20190212092625.GC27450@kroah.com>
Date:   Tue, 12 Feb 2019 10:26:25 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Hugo Lefeuvre <hle@....eu.com>
Cc:     Jiri Slaby <jslaby@...e.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tty/nozomi: use pci_iomap instead of ioremap_nocache

On Sun, Feb 10, 2019 at 10:45:00PM +0100, Hugo Lefeuvre wrote:
> > Use pci_iomap instead of ioremap_nocache in nozomi_card_init(). This
> > is a cleaner way to do PCI MMIO (performs additional checks) and
> > allows to drop the manual call to pci_resource_start.
> > 
> > pci_iomap relies on ioremap for MMIO and thus has uncached behavior.
> 
> there's still something unclear to me about dc->card_type being used as
> size argument to ioremap_nocache().
> 
> dc->base_addr is the sum of all six io region lengths, not the size of
> region 0 which we are trying to map here. Why not using the size of region
> 0 instead ?

No idea, that might just be how the card is layed out.

> If the goal is to map all six regions "at once", I'm not sure how this is
> supposed to work. Is there any kind of guarantee that all six regions will
> be adjacent?

For some reason, it must happen that way, otherwise the driver would not
work very well :)

> If this is a bug then this patch "somehow" already adresses it since
> pci_iomap calls pci_resource_len itself. Otherwise this patch is broken.

Let's apply it and see if anyone screams...

thanks,

greg k-h