netdev - Re: [PATCH net 13/13] can: kvaser_pciefd: Enable 64-bit DMA addressing

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Message-ID: <20240830131724.7c08eac4@kernel.org>
Date: Fri, 30 Aug 2024 13:17:24 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Marc Kleine-Budde <mkl@...gutronix.de>
Cc: netdev@...r.kernel.org, davem@...emloft.net, linux-can@...r.kernel.org,
 kernel@...gutronix.de, Martin Jocic <martin.jocic@...ser.com>
Subject: Re: [PATCH net 13/13] can: kvaser_pciefd: Enable 64-bit DMA
 addressing

On Thu, 29 Aug 2024 21:20:46 +0200 Marc Kleine-Budde wrote:
> +	if (IS_ENABLED(CONFIG_ARCH_DMA_ADDR_T_64BIT))
> +		dma_set_mask_and_coherent(&pcie->pci->dev, DMA_BIT_MASK(64));

This IS_ENABLED() is quite unusual. The driver just advertises its
capability of using 64 addressing. If the platform doesn't support
64b DMA addressing and therefore dma_addr_t is narrower, everything
will still work. I could be wrong, but that's how I understand it.