From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from eu1sys200aog118.obsmtp.com ([207.126.144.145]:43492 "EHLO eu1sys200aog118.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752265Ab2BWKBw (ORCPT ); Thu, 23 Feb 2012 05:01:52 -0500 Message-ID: <4F460E79.5000308@st.com> Date: Thu, 23 Feb 2012 15:31:29 +0530 From: Pratyush Anand MIME-Version: 1.0 To: Cc: "Pedanekar, Hemant" , "linux-pci@vger.kernel.org" , Viresh KUMAR , Shiraz HASHIM , Armando VISCONTI , Vipin KUMAR , Deepak SIKRI , Rajeev KUMAR , Vipul Kumar SAMAR , Amit VIRDI , Bhupesh SHARMA Subject: Re: [PATCH] PCIE: pcie_set_readrq must not be allowed by PCIE EP driver References: <1297937650-2558-1-git-send-email-pratyush.anand@st.com> <2A3DCF3DA181AD40BDE86A3150B27B6B0373799132@dbde02.ent.ti.com> <2A3DCF3DA181AD40BDE86A3150B27B6B03737991EA@dbde02.ent.ti.com> <4D78D6E3.50004@st.com> <2A3DCF3DA181AD40BDE86A3150B27B6B03743048FE@dbde02.ent.ti.com> <4D806132.1090704@st.com> In-Reply-To: <4D806132.1090704@st.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Sender: linux-pci-owner@vger.kernel.org List-ID: Hi Tejun, Its a long pending patch. Any decision on this patch. Regards Pratyush On 3/16/2011 12:35 PM, pratyush wrote: > Hello Hemant, > > On 3/16/2011 9:43 AM, Pedanekar, Hemant wrote: >>> What happens in your case? Does it not work, if you do not >>>> modify sil driver? >>>> >> I also require to modify the sil driver to avoid setting max RRQ to 4096 >> otherwise the data transfer over PCIe does not work. The RC responds with >> "Unsupported Request" for read request of size greater than 256 bytes. >> >> The other problem is, there is no way for peers to know that the other >> device cannot handle RRQ of size beyond certain limit. At least I am not >> aware of any bits in PCIe configuration space which advertise this. Do you >> know of any such? >> >> While, there is "Max RRQ size" field in device control register which only >> controls outbound RRQ size. >> >> This restriction probbaly will complicate more when the device with such >> RRQ limitation is a EP, in such case, no one else than the EP (and its driver) >> would know about this limitation and need to force others (including RC) to >> reduce the max RRQ size. >> > > Yes, I am agreed with you. I do not see any way to inform its peers about request > limit. So I think that a EP driver should not be allowed to call any function which > changes EP's RRQ size. It should always be RC driver which sets these values as > per max capability of the link. > > Currently I am managing it with postinit hook of RC driver. But can be part of > common pci stack. > > You can see my way of handling it at > http://www.spinics.net/lists/linux-pci/msg09897.html > > Regards > Pratyush