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Wysocki" , Kirti Wankhede , Jeremy Kerr , Rajat Jain , Jianxiong Gao , Dave Jiang , Saravana Kannan , Mauro Carvalho Chehab , openbmc@lists.ozlabs.org, devicetree@vger.kernel.org, Konrad Rzeszutek Wilk , Alex Williamson , Rob Herring , Bhaskar Chowdhury , Thomas Gleixner , Andrew Jeffery , Cornelia Huck , linux-kernel@vger.kernel.org, Vinod Koul , dmaengine@vger.kernel.org Subject: Re: [PATCH 4/5] driver core: inhibit automatic driver binding on reserved devices Message-ID: References: <20211022020032.26980-5-zev@bewilderbeest.net> <627101ee-7414-57d1-9952-6e023b8db317@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="190gZ0lVdnV/mRoG" Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --190gZ0lVdnV/mRoG Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Oct 25, 2021 at 03:58:25PM +0300, Andy Shevchenko wrote: > On Mon, Oct 25, 2021 at 06:44:26AM -0500, Patrick Williams wrote: > > On Mon, Oct 25, 2021 at 08:15:41AM +0200, Greg Kroah-Hartman wrote: > > > On Mon, Oct 25, 2021 at 12:38:08AM -0500, Frank Rowand wrote: > > > > On 10/23/21 3:56 AM, Greg Kroah-Hartman wrote: > > =20 > > > We have the bind/unbind ability today, from userspace, that can contr= ol > > > this. Why not just have Linux grab the device when it boots, and then > > > when userspace wants to "give the device up", it writes to "unbind" in > > > sysfs, and then when all is done, it writes to the "bind" file and th= en > > > Linux takes back over. > > >=20 > > > Unless for some reason Linux should _not_ grab the device when bootin= g, > > > then things get messier, as we have seen in this thread. > >=20 > > This is probably more typical on a BMC than atypical. The systems ofte= n require > > the BMC (running Linux) to be able to reboot independently from the man= aged host > > (running anything). In the example Zev gave, the BMC rebooting would r= ip away > > the BIOS chip from the running host. > >=20 > > The BMC almost always needs to come up in a "I don't know what could po= ssibly be > > going on in the system" state and re-discover where the system was left= off. >=20 > Isn't it an architectural issue then? I'm not sure what "it" you are referring to here. I was trying to explain why starting in "bind" state is not a good idea for= a BMC in most of these cases where we want to be able to dynamically add a de= vice. --=20 Patrick Williams --190gZ0lVdnV/mRoG Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEBGD9ii4LE9cNbqJBqwNHzC0AwRkFAmF2rwMACgkQqwNHzC0A wRk9Jw//e7gf0atu+Jk54NpG8wRJo875a0T6uIfxMH3+j8JgwRu5aEeH4Z4V02pk s2Zwvy4l6o0lIcgLCAWYQfpmV5E6vNBSn1ymXNW0RpY7ZhheqKKi2FFDuJwxgIgE j+IZUGzSXYD5Ttwf/FPG98BX7/cdlJGsvoMpjrQoegPC8e6CYVnOpkGF0rjZJSid DXopkEnAhkRURQlh46yH1j83UZOFxDfOY3KP7XLcc4aPYBYm+y76WbZQON8aNdZG o1uOYbSKxaZ+z6ZDyPWD1GA46ZrpYpEUeTypmW9a1g9d6ot45oK6I9lp+qRGwWoy 4spswa4MMv6BqcYnw/iXLpFQOi8h/7XO49yuF/O6Bu3b9xOvvfduxGWMervBarbs q+SDU1k6U23uLlp40hmTzmFxdnH4YlB1/vLdP5aIsaVsWzyzYIh1AP3aIHmPFpwI DRPQ3WZu792khszBv/SNDkGuO3SJpgXYT+eakB1TofbkBaPtbjK88wmfs5rh1kyW QUrQUpQIuUDmhzyb8ELGFWb4/cWHYiKKyKV6+ynKXhzdXLGUQxslR1uM687DJxcI gmhK+d2uLQh+UHRDyZqH28oUmfpc0V5TukpV2PkBi0Nm9K6X6baYNsnAOwLAB5ya 5F81+hR5s1AQFaGPxqQzTSsbh33SjZyXG/5kMtLr2xnaHAToxrQ= =r9se -----END PGP SIGNATURE----- --190gZ0lVdnV/mRoG--