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From: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
To: Mian Yousaf Kaukab <ykaukab-l3A5Bk7waGM@public.gmane.org>
Cc: robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
	robin.murphy-5wv7dgnIgG8@public.gmane.org,
	devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	talho-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org,
	thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
	jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org,
	linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	afaerber-l3A5Bk7waGM@public.gmane.org,
	arnd-r2nGTMty4D4@public.gmane.org,
	gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org
Subject: Re: [PATCH 2/4] dt-bindings: sram: add documentation for reserved-only flag
Date: Tue, 12 May 2020 13:45:28 -0600	[thread overview]
Message-ID: <52f099e4-5c03-2141-f049-cd3adeb04c5b@wwwdotorg.org> (raw)
In-Reply-To: <20200512144803.24344-2-ykaukab-l3A5Bk7waGM@public.gmane.org>

On 5/12/20 8:48 AM, Mian Yousaf Kaukab wrote:
> Add documentation for the new optional flag added for SRAM driver.

> diff --git a/Documentation/devicetree/bindings/sram/sram.yaml b/Documentation/devicetree/bindings/sram/sram.yaml

> +  reserved-only:
> +    description:
> +      The flag indicating, that only SRAM reserved regions have to be remapped.
> +      remapping type is selected depending upon no-memory-wc as usual.
> +    type: boolean

This feels a bit like a SW flag rather than a HW description, so I'm not
sure it's appropriate to put it into DT.

Are there any cases where the SW should map all of the SRAM, i.e. where
we wouldn't expect to set reserved-only? I'd expect reserved-only to be
the default, and perhaps only, mode of operation for the SRAM driver. If
we can't do that because some SW currently expects to be able to map
arbitrary portions of the SRAM, shouldn't that SW be fixed to tell the
SRAM driver which parts it's using, hence still allowing the driver to
only map in-use portions?

WARNING: multiple messages have this Message-ID (diff)
From: Stephen Warren <swarren@wwwdotorg.org>
To: Mian Yousaf Kaukab <ykaukab@suse.de>
Cc: robh+dt@kernel.org, robin.murphy@arm.com,
	devicetree@vger.kernel.org, talho@nvidia.com,
	thierry.reding@gmail.com, jonathanh@nvidia.com,
	linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, afaerber@suse.de,
	arnd@arndb.de, gregkh@linuxfoundation.org
Subject: Re: [PATCH 2/4] dt-bindings: sram: add documentation for reserved-only flag
Date: Tue, 12 May 2020 13:45:28 -0600	[thread overview]
Message-ID: <52f099e4-5c03-2141-f049-cd3adeb04c5b@wwwdotorg.org> (raw)
In-Reply-To: <20200512144803.24344-2-ykaukab@suse.de>

On 5/12/20 8:48 AM, Mian Yousaf Kaukab wrote:
> Add documentation for the new optional flag added for SRAM driver.

> diff --git a/Documentation/devicetree/bindings/sram/sram.yaml b/Documentation/devicetree/bindings/sram/sram.yaml

> +  reserved-only:
> +    description:
> +      The flag indicating, that only SRAM reserved regions have to be remapped.
> +      remapping type is selected depending upon no-memory-wc as usual.
> +    type: boolean

This feels a bit like a SW flag rather than a HW description, so I'm not
sure it's appropriate to put it into DT.

Are there any cases where the SW should map all of the SRAM, i.e. where
we wouldn't expect to set reserved-only? I'd expect reserved-only to be
the default, and perhaps only, mode of operation for the SRAM driver. If
we can't do that because some SW currently expects to be able to map
arbitrary portions of the SRAM, shouldn't that SW be fixed to tell the
SRAM driver which parts it's using, hence still allowing the driver to
only map in-use portions?

WARNING: multiple messages have this Message-ID (diff)
From: Stephen Warren <swarren@wwwdotorg.org>
To: Mian Yousaf Kaukab <ykaukab@suse.de>
Cc: devicetree@vger.kernel.org, arnd@arndb.de,
	gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
	robh+dt@kernel.org, jonathanh@nvidia.com, talho@nvidia.com,
	thierry.reding@gmail.com, linux-tegra@vger.kernel.org,
	robin.murphy@arm.com, afaerber@suse.de,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/4] dt-bindings: sram: add documentation for reserved-only flag
Date: Tue, 12 May 2020 13:45:28 -0600	[thread overview]
Message-ID: <52f099e4-5c03-2141-f049-cd3adeb04c5b@wwwdotorg.org> (raw)
In-Reply-To: <20200512144803.24344-2-ykaukab@suse.de>

On 5/12/20 8:48 AM, Mian Yousaf Kaukab wrote:
> Add documentation for the new optional flag added for SRAM driver.

> diff --git a/Documentation/devicetree/bindings/sram/sram.yaml b/Documentation/devicetree/bindings/sram/sram.yaml

> +  reserved-only:
> +    description:
> +      The flag indicating, that only SRAM reserved regions have to be remapped.
> +      remapping type is selected depending upon no-memory-wc as usual.
> +    type: boolean

This feels a bit like a SW flag rather than a HW description, so I'm not
sure it's appropriate to put it into DT.

Are there any cases where the SW should map all of the SRAM, i.e. where
we wouldn't expect to set reserved-only? I'd expect reserved-only to be
the default, and perhaps only, mode of operation for the SRAM driver. If
we can't do that because some SW currently expects to be able to map
arbitrary portions of the SRAM, shouldn't that SW be fixed to tell the
SRAM driver which parts it's using, hence still allowing the driver to
only map in-use portions?

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2020-05-12 19:45 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-12 14:48 [PATCH 1/4] misc: sram: add support for remapping reserved regions only Mian Yousaf Kaukab
2020-05-12 14:48 ` Mian Yousaf Kaukab
2020-05-12 14:48 ` Mian Yousaf Kaukab
     [not found] ` <20200512144803.24344-1-ykaukab-l3A5Bk7waGM@public.gmane.org>
2020-05-12 14:48   ` [PATCH 2/4] dt-bindings: sram: add documentation for reserved-only flag Mian Yousaf Kaukab
2020-05-12 14:48     ` Mian Yousaf Kaukab
2020-05-12 14:48     ` Mian Yousaf Kaukab
     [not found]     ` <20200512144803.24344-2-ykaukab-l3A5Bk7waGM@public.gmane.org>
2020-05-12 19:45       ` Stephen Warren [this message]
2020-05-12 19:45         ` Stephen Warren
2020-05-12 19:45         ` Stephen Warren
     [not found]         ` <52f099e4-5c03-2141-f049-cd3adeb04c5b-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2020-05-13 10:41           ` Mian Yousaf Kaukab
2020-05-13 10:41             ` Mian Yousaf Kaukab
2020-05-13 10:41             ` Mian Yousaf Kaukab
     [not found]             ` <20200513104127.GA2309-l3A5Bk7waGM@public.gmane.org>
2020-05-19 16:16               ` Stephen Warren
2020-05-19 16:16                 ` Stephen Warren
2020-05-19 16:16                 ` Stephen Warren
     [not found]                 ` <efcc6b5e-423c-8ae1-8a46-d6a06c1a1bab-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2020-05-19 23:03                   ` Rob Herring
2020-05-19 23:03                     ` Rob Herring
2020-05-19 23:03                     ` Rob Herring
2020-05-20  8:55                     ` Thierry Reding
2020-05-20  8:55                       ` Thierry Reding
2020-05-26 15:28                       ` Mian Yousaf Kaukab
2020-05-26 15:28                         ` Mian Yousaf Kaukab
2020-05-26 15:28                         ` Mian Yousaf Kaukab
2020-05-20  8:40               ` Thierry Reding
2020-05-20  8:40                 ` Thierry Reding
2020-05-20  8:40                 ` Thierry Reding
2020-05-12 14:48   ` [PATCH 3/4] arm64: tegra186: add reserved-only flag in sysram node Mian Yousaf Kaukab
2020-05-12 14:48     ` Mian Yousaf Kaukab
2020-05-12 14:48     ` Mian Yousaf Kaukab
2020-05-12 14:48 ` [PATCH 4/4] arm64: tegra194: " Mian Yousaf Kaukab
2020-05-12 14:48   ` Mian Yousaf Kaukab

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