On Tue, Dec 05, 2023 at 07:18:29PM +0100, Hardik Gajjar wrote: > There is a potential delay in notifying Linux USB drivers of downstream > USB bus activity when connecting a high-speed or superSpeed device via the > Microchip USB491x hub. This delay is due to the fixed bInterval value of > 12 in the silicon of the Microchip USB491x hub. > > Microchip requested to ignore the device descriptor and decrease that > value to 9 as it was too late to modify that in silicon. > > This patch speeds up the USB enummeration process that helps to pass > Apple Carplay certifications and improve the User experience when utilizing > the USB device via Microchip Multihost USB491x Hub. > > A new hub quirk HUB_QUIRK_REDUCE_FRAME_INTR_BINTERVAL speeds up > the notification process for Microchip USB491x hub by limiting > the maximum bInterval value to 9. > > Signed-off-by: Hardik Gajjar <hgajjar@xxxxxxxxxxxxxx> > --- > changes since version 1: > - Move implementation from config.c and quirk.c to hub.c as this is hub > specific changes. > - Improve commit message. > - Link to v1 - https://lore.kernel.org/all/20231123081948.58776-1-hgajjar@xxxxxxxxxxxxxx/ > > changes since version 2: > - Call usb_set_interface after updating the bInterval to Tell the HCD about modification > - Link to v2 - https://lore.kernel.org/all/20231130084855.119937-1-hgajjar@xxxxxxxxxxxxxx/ > > changes since version 3: > - Change HUB_QUIRK_REDUCE_FRAME_INTR_BINTERVAL value from 0x08 to 0x04 > - Link to v3 - https://lore.kernel.org/all/20231201144705.97385-1-hgajjar@xxxxxxxxxxxxxx/ > > changes since version 4: > - change quirk hardcoded value to BIT() Macro > - Link to v4 - https://lore.kernel.org/all/20231204073834.112509-1-hgajjar@xxxxxxxxxxxxxx/ > --- Reviewed-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
