From: Tony Lindgren <tony@atomide.com>
To: Tero Kristo <t-kristo@ti.com>
Cc: Roger Quadros <rogerq@ti.com>,
hch@lst.de, robin.murphy@arm.com, robh+dt@kernel.org, nm@ti.com,
nsekhar@ti.com, linux-omap@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ARM: dts: dra7: Add bus_dma_limit for L3 bus
Date: Tue, 10 Mar 2020 08:48:29 -0700 [thread overview]
Message-ID: <20200310154829.GS37466@atomide.com> (raw)
In-Reply-To: <e7df4db7-6fe1-cfa4-841b-ddd395864bb8@ti.com>
* Tero Kristo <t-kristo@ti.com> [200310 14:46]:
> On 10/03/2020 13:53, Roger Quadros wrote:
> > The L3 interconnect can access only 32-bits of address.
> > Add the dma-ranges property to reflect this limit.
> >
> > This will ensure that no device under L3 is
> > given > 32-bit address for DMA.
> >
> > Issue was observed only with SATA on DRA7-EVM with 4GB RAM
> > and CONFIG_ARM_LPAE enabled. This is because the controller
> > can perform 64-bit DMA and was setting the dma_mask to 64-bit.
> >
> > Setting the correct bus_dma_limit fixes the issue.
>
> This seems kind of messy to modify almost every DT node because of this....
> Are you sure this is the only way to get it done? No way to modify the sata
> node only which is impacted somehow?
>
> Also, what if you just pass 0xffffffff to the dma-ranges property? That
> would avoid modifying every node I guess.
Also, I think these interconnects are not limited to 32-bit access.
So yeah I too would prefer a top level dma-ranges property assuming
that works.
I guess there dma-ranges should not be 0xffffffff though if
limited to 2GB :)
Regards,
Tony
next prev parent reply other threads:[~2020-03-10 15:48 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-10 11:53 [PATCH] ARM: dts: dra7: Add bus_dma_limit for L3 bus Roger Quadros
2020-03-10 14:45 ` Tero Kristo
2020-03-10 15:48 ` Tony Lindgren [this message]
2020-03-10 16:16 ` Robin Murphy
2020-03-11 7:13 ` Roger Quadros
2020-03-11 10:28 ` Roger Quadros
2020-03-11 12:25 ` Robin Murphy
2020-03-11 7:20 ` Roger Quadros
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