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[73.252.146.110]) by smtp.gmail.com with ESMTPSA id d22sm2030774pgh.11.2020.04.06.23.02.50 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 06 Apr 2020 23:02:51 -0700 (PDT) Date: Mon, 6 Apr 2020 23:02:43 -0700 From: Tao Ren To: Benjamin Herrenschmidt Cc: Felipe Balbi , Greg Kroah-Hartman , Joel Stanley , Andrew Jeffery , Chunfeng Yun , Stephen Boyd , linux-usb@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org, openbmc@lists.ozlabs.org, taoren@fb.com Subject: Re: [PATCH v3] usb: gadget: aspeed: improve vhub port irq handling Message-ID: <20200407060242.GA15050@taoren-ubuntu-R90MNF91> References: <20200315191430.12379-1-rentao.bupt@gmail.com> <20200401215826.GA8248@taoren-ubuntu-R90MNF91> <512d625e45ea953d722bb7ea73c3619730312284.camel@kernel.crashing.org> <20200403064826.GA10866@taoren-ubuntu-R90MNF91> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200403064826.GA10866@taoren-ubuntu-R90MNF91> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Ben, On Thu, Apr 02, 2020 at 11:48:27PM -0700, Tao Ren wrote: > On Thu, Apr 02, 2020 at 09:45:38PM +1100, Benjamin Herrenschmidt wrote: > > On Wed, 2020-04-01 at 14:58 -0700, Tao Ren wrote: > > > Hi Ben, > > > > > > Any further comments on the patch? > > > > Ah sorry, nope. Did you check the generated assembly to see if it > > looked any better ? :-) > > > > Otherwise, > > > > Acked-by: Benjamin Herrenschmidt > > Thanks Ben for the review. Let me see if I can collect some runtime data > on my ast2400 BMC platform. Will update back later. I ran some testing on my ast2400 and ast2500 BMC and looks like the for() loop runs faster than for_each_set_bit_from() loop in my environment. I'm not sure if something needs to be revised in my test code, but please kindly share your suggestions: I use get_cycles() to calculate execution time of 2 different loops, and ast_vhub_dev_irq() is replaced with barrier() to avoid "noise"; below are the results: - when downstream port number is 5 and only 1 irq bit is set, it takes ~30 cycles to finish for_each_set_bit() loop, and 20-25 cycles to finish the for() loop. - if downstream port number is 5 and all 5 bits are set, then for_each_set_bit() loop takes ~50 cycles and for() loop takes ~25 cycles. - when I increase downsteam port number to 16 and set 1 irq bit, the for_each_set_bit() loop takes ~30 cycles and for() loop takes 25 cycles. It's a little surprise to me because I thought for() loop would cost 60+ cycles (3 times of the value when port number is 5). - if downstream port number is 16 and all irq status bits are set, then for_each_set_bit() loop takes 60-70 cycles and for() loop takes 30+ cycles. Cheers, Tao > > > > > > > On Sun, Mar 15, 2020 at 12:14:30PM -0700, rentao.bupt@gmail.com > > > wrote: > > > > From: Tao Ren > > > > > > > > This patch evaluates vhub ports' irq mask before going through per- > > > > port > > > > irq handling one by one, which helps to speed up irq handling in > > > > case > > > > there is no port interrupt. > > > > > > > > Signed-off-by: Tao Ren > > > > --- > > > > Changes in v3: > > > > - assign istat to (unsigned long) bitmap before calling > > > > "for_each_set_bit_from". > > > > Changes in v2: > > > > - use "for_each_set_bit" to speed up port irq handling. > > > > > > > > drivers/usb/gadget/udc/aspeed-vhub/core.c | 12 +++++++++--- > > > > drivers/usb/gadget/udc/aspeed-vhub/vhub.h | 8 +++----- > > > > 2 files changed, 12 insertions(+), 8 deletions(-) > > > > > > > > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c > > > > b/drivers/usb/gadget/udc/aspeed-vhub/core.c > > > > index f8d35dd60c34..555e8645fb1e 100644 > > > > --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c > > > > +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c > > > > @@ -134,11 +134,15 @@ static irqreturn_t ast_vhub_irq(int irq, void > > > > *data) > > > > } > > > > > > > > /* Handle device interrupts */ > > > > - for (i = 0; i < vhub->max_ports; i++) { > > > > - u32 dev_mask = VHUB_IRQ_DEVICE1 << i; > > > > + if (istat & vhub->port_irq_mask) { > > > > + unsigned long bitmap = istat; > > > > + int offset = VHUB_IRQ_DEV1_BIT; > > > > + int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports; > > > > > > > > - if (istat & dev_mask) > > > > + for_each_set_bit_from(offset, &bitmap, size) { > > > > + i = offset - VHUB_IRQ_DEV1_BIT; > > > > ast_vhub_dev_irq(&vhub->ports[i].dev); > > > > + } > > > > } > > > > > > > > /* Handle top-level vHub EP0 interrupts */ > > > > @@ -332,6 +336,8 @@ static int ast_vhub_probe(struct > > > > platform_device *pdev) > > > > > > > > spin_lock_init(&vhub->lock); > > > > vhub->pdev = pdev; > > > > + vhub->port_irq_mask = GENMASK(VHUB_IRQ_DEV1_BIT + vhub- > > > > >max_ports - 1, > > > > + VHUB_IRQ_DEV1_BIT); > > > > > > > > res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > > > > vhub->regs = devm_ioremap_resource(&pdev->dev, res); > > > > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h > > > > b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h > > > > index fac79ef6d669..23a1ac91f8d2 100644 > > > > --- a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h > > > > +++ b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h > > > > @@ -51,14 +51,11 @@ > > > > #define VHUB_CTRL_UPSTREAM_CONNECT (1 << 0) > > > > > > > > /* IER & ISR */ > > > > +#define VHUB_IRQ_DEV1_BIT 9 > > > > #define VHUB_IRQ_USB_CMD_DEADLOCK (1 << 18) > > > > #define VHUB_IRQ_EP_POOL_NAK (1 << 17) > > > > #define VHUB_IRQ_EP_POOL_ACK_STALL (1 << 16) > > > > -#define VHUB_IRQ_DEVICE5 (1 << 13) > > > > -#define VHUB_IRQ_DEVICE4 (1 << 12) > > > > -#define VHUB_IRQ_DEVICE3 (1 << 11) > > > > -#define VHUB_IRQ_DEVICE2 (1 << 10) > > > > -#define VHUB_IRQ_DEVICE1 (1 << 9) > > > > +#define VHUB_IRQ_DEVICE1 (1 << > > > > (VHUB_IRQ_DEV1_BIT)) > > > > #define VHUB_IRQ_BUS_RESUME (1 << 8) > > > > #define VHUB_IRQ_BUS_SUSPEND (1 << 7) > > > > #define VHUB_IRQ_BUS_RESET (1 << 6) > > > > @@ -402,6 +399,7 @@ struct ast_vhub { > > > > /* Per-port info */ > > > > struct ast_vhub_port *ports; > > > > u32 max_ports; > > > > + u32 port_irq_mask; > > > > > > > > /* Generic EP data structures */ > > > > struct ast_vhub_ep *epns; > > > > -- > > > > 2.17.1 > > > > > >