From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Sumit Semwal <sumit.semwal@linaro.org>
Cc: linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
t.stanislaws@samsung.com, linaro-kernel@lists.linaro.org,
robdclark@gmail.com, daniel@ffwll.ch, m.szyprowski@samsung.com
Subject: Re: [RFCv2 2/2] dma-buf: add helpers for sharing attacher constraints with dma-parms
Date: Wed, 21 Jan 2015 17:31:28 +0000 [thread overview]
Message-ID: <20150121173128.GV26493@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1421813807-9178-3-git-send-email-sumit.semwal@linaro.org>
On Wed, Jan 21, 2015 at 09:46:47AM +0530, Sumit Semwal wrote:
> +static int calc_constraints(struct device *dev,
> + struct dma_buf_constraints *calc_cons)
> +{
> + struct dma_buf_constraints cons = *calc_cons;
> +
> + cons.dma_mask &= dma_get_mask(dev);
I don't think this makes much sense when you consider that the DMA
infrastructure supports buses with offsets. The DMA mask is th
upper limit of the _bus_ specific address, it is not a mask per-se.
What this means is that &= is not the right operation. Moreover,
simply comparing masks which could be from devices on unrelated
buses doesn't make sense either.
However, that said, I don't have an answer for what you want to
achieve here.
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
WARNING: multiple messages have this Message-ID (diff)
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Sumit Semwal <sumit.semwal@linaro.org>
Cc: linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
t.stanislaws@samsung.com, linaro-kernel@lists.linaro.org,
robdclark@gmail.com, daniel@ffwll.ch, m.szyprowski@samsung.com
Subject: Re: [RFCv2 2/2] dma-buf: add helpers for sharing attacher constraints with dma-parms
Date: Wed, 21 Jan 2015 17:31:28 +0000 [thread overview]
Message-ID: <20150121173128.GV26493@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1421813807-9178-3-git-send-email-sumit.semwal@linaro.org>
On Wed, Jan 21, 2015 at 09:46:47AM +0530, Sumit Semwal wrote:
> +static int calc_constraints(struct device *dev,
> + struct dma_buf_constraints *calc_cons)
> +{
> + struct dma_buf_constraints cons = *calc_cons;
> +
> + cons.dma_mask &= dma_get_mask(dev);
I don't think this makes much sense when you consider that the DMA
infrastructure supports buses with offsets. The DMA mask is th
upper limit of the _bus_ specific address, it is not a mask per-se.
What this means is that &= is not the right operation. Moreover,
simply comparing masks which could be from devices on unrelated
buses doesn't make sense either.
However, that said, I don't have an answer for what you want to
achieve here.
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
--
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WARNING: multiple messages have this Message-ID (diff)
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFCv2 2/2] dma-buf: add helpers for sharing attacher constraints with dma-parms
Date: Wed, 21 Jan 2015 17:31:28 +0000 [thread overview]
Message-ID: <20150121173128.GV26493@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1421813807-9178-3-git-send-email-sumit.semwal@linaro.org>
On Wed, Jan 21, 2015 at 09:46:47AM +0530, Sumit Semwal wrote:
> +static int calc_constraints(struct device *dev,
> + struct dma_buf_constraints *calc_cons)
> +{
> + struct dma_buf_constraints cons = *calc_cons;
> +
> + cons.dma_mask &= dma_get_mask(dev);
I don't think this makes much sense when you consider that the DMA
infrastructure supports buses with offsets. The DMA mask is th
upper limit of the _bus_ specific address, it is not a mask per-se.
What this means is that &= is not the right operation. Moreover,
simply comparing masks which could be from devices on unrelated
buses doesn't make sense either.
However, that said, I don't have an answer for what you want to
achieve here.
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
WARNING: multiple messages have this Message-ID (diff)
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Sumit Semwal <sumit.semwal@linaro.org>
Cc: t.stanislaws@samsung.com, linaro-kernel@lists.linaro.org,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org,
m.szyprowski@samsung.com, linux-arm-kernel@lists.infradead.org,
linux-media@vger.kernel.org
Subject: Re: [RFCv2 2/2] dma-buf: add helpers for sharing attacher constraints with dma-parms
Date: Wed, 21 Jan 2015 17:31:28 +0000 [thread overview]
Message-ID: <20150121173128.GV26493@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1421813807-9178-3-git-send-email-sumit.semwal@linaro.org>
On Wed, Jan 21, 2015 at 09:46:47AM +0530, Sumit Semwal wrote:
> +static int calc_constraints(struct device *dev,
> + struct dma_buf_constraints *calc_cons)
> +{
> + struct dma_buf_constraints cons = *calc_cons;
> +
> + cons.dma_mask &= dma_get_mask(dev);
I don't think this makes much sense when you consider that the DMA
infrastructure supports buses with offsets. The DMA mask is th
upper limit of the _bus_ specific address, it is not a mask per-se.
What this means is that &= is not the right operation. Moreover,
simply comparing masks which could be from devices on unrelated
buses doesn't make sense either.
However, that said, I don't have an answer for what you want to
achieve here.
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2015-01-21 17:31 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-21 4:16 [RFCv2 0/2] dma-parms, constraints and helpers for dma-buf Sumit Semwal
2015-01-21 4:16 ` Sumit Semwal
2015-01-21 4:16 ` Sumit Semwal
2015-01-21 4:16 ` Sumit Semwal
2015-01-21 4:16 ` [RFCv2 1/2] device: add dma_params->max_segment_count Sumit Semwal
2015-01-21 4:16 ` Sumit Semwal
2015-01-21 4:16 ` Sumit Semwal
2015-01-21 18:56 ` Robin Murphy
2015-01-21 18:56 ` Robin Murphy
2015-01-21 18:56 ` Robin Murphy
2015-01-21 18:56 ` Robin Murphy
2015-01-22 3:46 ` Sumit Semwal
2015-01-22 3:46 ` Sumit Semwal
2015-01-22 3:46 ` Sumit Semwal
2015-01-22 3:46 ` Sumit Semwal
2015-01-21 4:16 ` [RFCv2 2/2] dma-buf: add helpers for sharing attacher constraints with dma-parms Sumit Semwal
2015-01-21 4:16 ` Sumit Semwal
2015-01-21 4:16 ` Sumit Semwal
2015-01-21 4:16 ` Sumit Semwal
2015-01-21 17:31 ` Russell King - ARM Linux [this message]
2015-01-21 17:31 ` Russell King - ARM Linux
2015-01-21 17:31 ` Russell King - ARM Linux
2015-01-21 17:31 ` Russell King - ARM Linux
2015-01-27 7:04 ` Sumit Semwal
2015-01-27 7:04 ` Sumit Semwal
2015-01-27 7:04 ` Sumit Semwal
2015-01-27 7:04 ` Sumit Semwal
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