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Tue, 21 Apr 2026 13:18:09 -0700 (PDT) Date: Tue, 21 Apr 2026 16:18:07 -0400 From: Alan Stern To: =?iso-8859-1?Q?Bj=F8rn?= Mork Cc: Xu Yang , gregkh@linuxfoundation.org, khtsai@google.com, kexinsun@smail.nju.edu.cn, hhhuuu@google.com, kees@kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, imx@lists.linux.dev, jun.li@nxp.com Subject: Re: [PATCH] usb: gadget: udc: skip pullup() if already connected Message-ID: <40ab2813-e583-484e-990b-1a3651e0bbb4@rowland.harvard.edu> References: <20260421082050.1260823-1-xu.yang_2@nxp.com> <87v7dkpc4b.fsf@miraculix.mork.no> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87v7dkpc4b.fsf@miraculix.mork.no> On Tue, Apr 21, 2026 at 05:27:32PM +0200, Bjørn Mork wrote: > Alan Stern writes: > > > This patch is wrong. To see why, read the comments just below the end > > of the patch and see also usb_gadget_activate(). > > > Made me look... > > Must say. This strikes me as a nice way to filter out humans from the > rest of the submitters: > > gadget->connected = true; > goto out; > } > > ret = gadget->ops->pullup(gadget, 1); > if (!ret) > gadget->connected = 1; > > > The indecisiveness looks strange. There's a nice symmetry with > usb_gadget_disconnect_locked() though: > > gadget->connected = false; > goto out; > } > > ret = gadget->ops->pullup(gadget, 0); > if (!ret) > gadget->connected = 0; Granted, it does look a little strange. ->connected is actually a 1-bit bitfield, though, so treating it as a boolean instead of an integer is not completely beyond the bounds of reason. > What surprised me most was that the different variants were added by the > same commit > ccdf138fe3e2 ("usb: gadget: add usb_gadget_activate/deactivate functions"). But this isn't what my rejection was complaining about. The patch's problem was functional, not aesthetic. Alan Stern