From: "Valdis Klētnieks" <valdis.kletnieks@vt.edu>
To: "s.achterop@rug.nl" <s.achterop@rug.nl>
Cc: kernelnewbies@kernelnewbies.org
Subject: Re: Trouble with allocating memory on platform driver
Date: Fri, 17 Apr 2020 15:30:42 -0400 [thread overview]
Message-ID: <147577.1587151842@turing-police> (raw)
In-Reply-To: <f322b7ae-93c2-1dc0-21a7-b26402d5aaad@rug.nl>
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On Fri, 17 Apr 2020 10:47:33 +0200, "s.achterop@rug.nl" said:
> I found a working solution. I actually don't know what I am doing but it works.
> Before the call to dma_zalloc_coherent I added:
>
> pdev->dev.coherent_dma_mask = 0xffffffff;
DMA_BIT_MASK(32) rather than a hex constant would be a better choice.
>
> Now it works.
Note that "works" and "is correct" are two different things. That should be
a mask that tells how many bits of the value are actually used by the hardware.
On most 32-bit systems, 32 will be correct, but there's other values in use
(on S/390, it's either 31 or 64 bits, the PowerPC can have 44, and the old PNP
stuff on x86 weirds out at the 24-bit line).
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prev parent reply other threads:[~2020-04-17 19:31 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-04 15:21 Trouble with allocating memory on platform driver s.achterop
2020-04-15 9:29 ` s.achterop
2020-04-17 8:47 ` s.achterop
2020-04-17 19:30 ` Valdis Klētnieks [this message]
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