From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rolf Eike Beer Subject: Re: SIL24: pcie_set_readrq 4096 Date: Fri, 23 Jul 2010 07:30:08 +0200 Message-ID: <201007230730.16935.eike-kernel@sf-tec.de> References: <4C48452D.5070207@kernel.org> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart1390805.6SlFWEIya1"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-pci-owner@vger.kernel.org To: Jassi Brar Cc: Tejun Heo , linux-pci@vger.kernel.org, linux-ide@vger.kernel.org, jgarzik@pobox.com List-Id: linux-ide@vger.kernel.org --nextPart1390805.6SlFWEIya1 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Jassi Brar wrote: > On Thu, Jul 22, 2010 at 10:18 PM, Tejun Heo wrote: > > It's been a while since I read pci-e spec but IIUC readrq size and > > payload size are independent and if readrq is larger than payload size > > it's supposed to complete in multiple steps. I could be wrong tho. >=20 > AFAIUI readrq size is independent and not greater than the max_payload > size. Payload size is what max a device can handle and readrq is what a > device can ask. The first and third statements are correct, the second is not. Read request= may=20 be larger than the usual payload size. However that is something the complete PCIe fabric up to that device has to= =20 support. So if the root port does only support read request of something=20 smaller the device must be configured with that maximum size so it will not= =20 issue any bigger requests. Blindly configuring a device to the maximum allo= wed=20 value looks dangerous and broken to me. Eike --nextPart1390805.6SlFWEIya1 Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.15 (GNU/Linux) iEYEABECAAYFAkxJKOgACgkQXKSJPmm5/E7wsgCdEZ0AamXoXiJ8fMTeBSEom5ul KJgAn32Ikd11NIad6aF8ZwQOvcjVEW6m =7KVk -----END PGP SIGNATURE----- --nextPart1390805.6SlFWEIya1--