From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lukasz Majewski Date: Wed, 20 Aug 2014 09:34:13 +0200 Subject: [U-Boot] [UBOOT RFC PATCH 07/13] usb: gadget: g_dnl: Explicitly set the max packet size in descriptor In-Reply-To: <20140819154402.GL16085@saruman.home> References: <1408372115-4570-1-git-send-email-kishon@ti.com> <1408372115-4570-8-git-send-email-kishon@ti.com> <20140818143856.GF9662@saruman.home> <20140818165646.4487059c@amdc2363> <53F36F58.7060308@ti.com> <20140819154402.GL16085@saruman.home> Message-ID: <20140820093413.21ab509d@amdc2363> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Felipe, > On Tue, Aug 19, 2014 at 09:08:00PM +0530, Kishon Vijay Abraham I > wrote: > > > > > > On Monday 18 August 2014 08:26 PM, Lukasz Majewski wrote: > > > Hi Kishon, > > > > > >>> Explicity set the max packet size in the device descriptor to > > >>> 0x40 as specified in the device class specification for device > > >>> firmware upgrade. Also changed debug to printf to explicitly > > >>> notify the user if the device has been enumerated. > > > > > > It seems like this patch slipped without my attention ... > > > > > > Hence, I'd like to ask why you must hardcode the packet size here? > > > > http://www.usb.org/developers/devclass_docs/usbdfu10.pdf (in > > section 4.2.1 DFU Mode Device Descriptor), specifies the > > bMaxPacketSize0 can be 8,16,32,64. And the value we get from > > gadget is 512. So hard coded it. > > as I mentioned, this should be changed on connection done interrupt. In the u-boot it is set up during binding the composite. > DFU has one of the poorest documentations for a USB Class and has some > moronic definitions. Frankly speaking I prefer to have the worst standard than some "brilliant" in house developed protocols. > What happens if you want ot run DFU with a > superspeed controller (such as dwc3) when connected to a superspeed > port. We cannot use ep0 packet size as 64, right ? Correct me if I'm wrong, but MaxPacket for SS ep0 is 2^9 = 512B. I'm curious if dfu-util will manage to handle ep0 MaxPacket size up to 512B. It not, then we shall be able to fallback to 64B. > That's why > hardcoding is bad ;-) > -- Best regards, Lukasz Majewski Samsung R&D Institute Poland (SRPOL) | Linux Platform Group