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[75.142.250.213]) by smtp.gmail.com with ESMTPSA id e19sm806862qkl.94.2020.10.20.07.13.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 20 Oct 2020 07:13:33 -0700 (PDT) Subject: Re: [PATCH 1/2] fpga: dfl: add driver_override support To: Xu Yilun Cc: mdf@kernel.org, linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, lgoncalv@redhat.com, hao.wu@intel.com References: <1602828151-24784-1-git-send-email-yilun.xu@intel.com> <1602828151-24784-2-git-send-email-yilun.xu@intel.com> <63d7730b-d9b8-c75d-16f6-3ebb507aabaa@redhat.com> <20201019040612.GA16172@yilunxu-OptiPlex-7050> <20201020071158.GC28746@yilunxu-OptiPlex-7050> From: Tom Rix Message-ID: <48cc1b5f-4bb1-260d-7b8b-9484d3f0a6ba@redhat.com> Date: Tue, 20 Oct 2020 07:13:31 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20201020071158.GC28746@yilunxu-OptiPlex-7050> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-fpga@vger.kernel.org On 10/20/20 12:11 AM, Xu Yilun wrote: >>>>> int __dfl_driver_register(struct dfl_driver *dfl_drv, struct module *owner) >>>>> { >>>>> - if (!dfl_drv || !dfl_drv->probe || !dfl_drv->id_table) >>>>> + if (!dfl_drv || !dfl_drv->probe) >>>> id_table is still needed for the normal case. >>>> >>>> Instead of removing this check, could you add something like >>>> >>>> || (!dfl_drv->is_override && !dfl_drv->id_table) >>> I don't think it is needed. Seems is_override and !id_table are duplicated >>> conditions for this implementation. And it may make confusing, e.g. could >>> a driver been force matched when is_override is not set? >>> >>> I think we could make it simple, if the dfl driver didn't provide the >>> id_table, normally it could not match any device. I think it could be >>> easily understood by dfl driver developers. >>> >> Then an ASSERT should be added in dfl_bus_match() for id_entry. > I didn't get your idea. What Assertion should be added for id_entry? > BUG_ON(id_entry == NULL)? Then dfl-uio-pdev can't be inserted before > driver_override is set. > > I think it is normal case that a driver is successfully registered but > doesn't match any device because it provides no id_table. Ok, i see your point. Thanks for the explanation. Tom > > Thanks, > Yilun. >