linux-kernel - Re: [PATCH v5] remoteproc: imx_dsp_rproc: add custom memory copy implementation for i.MX DSP Cores

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Message-ID: <37ad1463-c12c-f148-4fe3-07dab52e8e1b@nxp.com>
Date:   Thu, 2 Mar 2023 11:52:13 +0200
From:   Iuliana Prodan <iuliana.prodan@....com>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        "Iuliana Prodan (OSS)" <iuliana.prodan@....nxp.com>
Cc:     Bjorn Andersson <andersson@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        "S.J. Wang" <shengjiu.wang@....com>,
        Fabio Estevam <festevam@...il.com>,
        Daniel Baluta <daniel.baluta@....com>,
        linux-imx <linux-imx@....com>, linux-remoteproc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Pengutronix Kernel Team <kernel@...gutronix.de>
Subject: Re: [PATCH v5] remoteproc: imx_dsp_rproc: add custom memory copy
 implementation for i.MX DSP Cores

Hi Mathieu,

On 3/1/2023 8:56 PM, Mathieu Poirier wrote:
> On Wed, Mar 01, 2023 at 11:49:16AM -0700, Mathieu Poirier wrote:
>> Hi Iuliana,
>>
>> On Tue, Feb 21, 2023 at 07:03:56PM +0200, Iuliana Prodan (OSS) wrote:
>>> From: Iuliana Prodan <iuliana.prodan@....com>
>>>
>>> The IRAM is part of the HiFi DSP.
>>> According to hardware specification only 32-bits write are allowed
>>> otherwise we get a Kernel panic.
>>>
>>> Therefore add a custom memory copy and memset functions to deal with
>>> the above restriction.
>>>
>>> Signed-off-by: Iuliana Prodan <iuliana.prodan@....com>
>>> ---
>>> Changes since v4
>>> - use GENMASK;
>>> - s/ioread32/readl;
>>> - s/iowrite32/writel;
>>> - use for loop with writel instead of __iowrite32_copy;
>>> - update multi-line comment format.
>>>
>> This looks good now.  I will queue this on March 13th when 6.3-rc2 is out.
>>
> And out of curiosity, are the remote processors handled by imx_rproc.c also have
> the same 32-bit write constraints?  If so, it would be nice to have a patch that
> fixes that as well.  In such a case, imx_dsp_rproc_memcpy() and
> imx_dsp_rproc_memset() should be renamed to something more generic and re-used
> in imx_rproc.c.

None that I know of.

But, this restriction applies to any core who's writing to IRAM.
When one is writing from anywhere else in the system to IRAM, this is a 
PIF write.
And the inbound PIF writes are 32-bits at a time.

Thanks,

Iulia