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From:   Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
To:     Vineet Gupta <Vineet.Gupta1@synopsys.com>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Alexey Brodkin" <Alexey.Brodkin@synopsys.com>,
        "linux-snps-arc@lists.infradead.org" 
        <linux-snps-arc@lists.infradead.org>
Subject: Re: [PATCH 4/5] ARC: add support for DSP-enabled userspace
 applications
Thread-Topic: [PATCH 4/5] ARC: add support for DSP-enabled userspace
 applications
Thread-Index: AQHVvOALEgJG1jhHKUKrXAMj7igcXqfflg6AgAMuUuk=
Date:   Thu, 9 Jan 2020 19:01:46 +0000
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References: <20191227180347.3579-1-Eugeniy.Paltsev@synopsys.com>
 <20191227180347.3579-5-Eugeniy.Paltsev@synopsys.com>,<a3890ccb-e948-6ad6-c2ea-5b77b9d3a289@synopsys.com>
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Hi Vineet,=0A=
=0A=
>From: Vineet Gupta <vgupta@synopsys.com>=0A=
>On 12/27/19 10:03 AM, Eugeniy Paltsev wrote:=0A=
>> To be able to run DSP-enabled userspace applications we need to=0A=
>> save and restore following DSP-related registers:=0A=
>> At IRQ/exception entry/exit:=0A=
>>  * ACC0_GLO, ACC0_GHI, DSP_CTRL=0A=
>>  * ACC0_LO, ACC0_HI (we already save them as r58, r59 pair)=0A=
>> At context switch:=0A=
>>  * DSP_BFLY0, DSP_FFT_CTRL=0A=
[snip]=0A=
>> +=0A=
>> +#ifndef __ASSEMBLY__=0A=
>> +=0A=
>> +/* some defines to simplify config sanitize in kernel/setup.c */=0A=
>> +#if defined(CONFIG_ARC_DSP_KERNEL)    || \=0A=
>> +    defined(CONFIG_ARC_DSP_USERSPACE)=0A=
>> +#define ARC_DSP_HANDLED                      1=0A=
>> +#else=0A=
>> +#define ARC_DSP_HANDLED                      0=0A=
>> +#endif=0A=
>=0A=
>This is a really bad idea - u r introducing explicit include dependencies =
which=0A=
>can change even outside of arch changes !=0A=
>We've dealt with enough of these problems with current.h, so best to avoid=
, even=0A=
>if there is some code clutter.=0A=
=0A=
Hmm, would it be OK if I add this option as a private kconfig option?=0A=
I.E (for ARC_DSP_HANDLED):=0A=
=0A=
---------------->8----------------------=0A=
config ARC_DSP_HANDLED=0A=
	def_bool n=0A=
=0A=
choice=0A=
	prompt "DSP support"=0A=
	default ARC_DSP_NONE=0A=
	help=0A=
	  Depending on the configuration, CPU can contain DSP registers=0A=
	  (ACC0_GLO, ACC0_GHI, DSP_BFLY0, DSP_CTRL, DSP_FFT_CTRL).=0A=
	  Bellow is options describing how to handle these registers in=0A=
	  interrupt entry / exit and in context switch.=0A=
=0A=
config ARC_DSP_NONE=0A=
	bool "No DSP extension presence in HW"=0A=
	help=0A=
	  No DSP extension presence in HW=0A=
=0A=
config ARC_DSP_KERNEL=0A=
	bool "DSP extension in HW, no support for userspace"=0A=
	select ARC_HAS_ACCL_REGS=0A=
	select ARC_DSP_HANDLED=0A=
	help=0A=
	  DSP extension presence in HW, no support for DSP-enabled userspace=0A=
	  applications. We don't save / restore DSP registers and only do=0A=
	  some minimal preparations so userspace won't be able to break kernel=0A=
=0A=
config ARC_DSP_USERSPACE=0A=
	bool "Support DSP for userspace apps"=0A=
	select ARC_HAS_ACCL_REGS=0A=
	select ARC_DSP_HANDLED=0A=
	help=0A=
	  DSP extension presence in HW, support save / restore DSP registers to=0A=
	  run DSP-enabled userspace applications=0A=
endchoice=0A=
---------------->8----------------------=0A=
=0A=
---=0A=
 Eugeniy Paltsev=