From: Robin Murphy <robin.murphy@arm.com> To: broonie@kernel.org, nsaenzjulienne@suse.de, f.fainelli@gmail.com, rjui@broadcom.com, sbranden@broadcom.com Cc: bcm-kernel-feedback-list@broadcom.com, linux-spi@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, kernel@martin.sperl.org, lukas@wunner.de, linux-kernel@vger.kernel.org Subject: [PATCH 2/3] spi: bcm2835: Micro-optimise IRQ handler Date: Tue, 16 Jun 2020 01:09:28 +0100 [thread overview] Message-ID: <6b401cb521539caffab21f05b4c8cba6c9d27c6e.1592261248.git.robin.murphy@arm.com> (raw) In-Reply-To: <cover.1592261248.git.robin.murphy@arm.com> The IRQ handler only needs the struct spi_controller for the sake of the completion at the end of a transfer. Passing the struct bcm2835_spi directly as the IRQ data allows that level of indirection to be pushed into the completion path for the reverse lookup, and avoided entirely in all other cases. This saves one explicit load in the critical path, plus (for a GCC 8.3 build) two registers worth of stack frame overhead. Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- drivers/spi/spi-bcm2835.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c index 524a91e52111..aec70ac8911e 100644 --- a/drivers/spi/spi-bcm2835.c +++ b/drivers/spi/spi-bcm2835.c @@ -86,6 +86,7 @@ MODULE_PARM_DESC(polling_limit_us, * @clk: core clock, divided to calculate serial clock * @irq: interrupt, signals TX FIFO empty or RX FIFO ¾ full * @tfr: SPI transfer currently processed + * @ctlr: SPI controller reverse lookup * @tx_buf: pointer whence next transmitted byte is read * @rx_buf: pointer where next received byte is written * @tx_len: remaining bytes to transmit @@ -125,6 +126,7 @@ struct bcm2835_spi { struct clk *clk; int irq; struct spi_transfer *tfr; + struct spi_controller *ctlr; const u8 *tx_buf; u8 *rx_buf; int tx_len; @@ -362,8 +364,7 @@ static void bcm2835_spi_reset_hw(struct bcm2835_spi *bs) static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id) { - struct spi_controller *ctlr = dev_id; - struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr); + struct bcm2835_spi *bs = dev_id; u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS); /* @@ -387,7 +388,7 @@ static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id) /* Transfer complete - reset SPI HW */ bcm2835_spi_reset_hw(bs); /* wake up the framework */ - complete(&ctlr->xfer_completion); + complete(&bs->ctlr->xfer_completion); } return IRQ_HANDLED; @@ -1310,6 +1311,7 @@ static int bcm2835_spi_probe(struct platform_device *pdev) ctlr->dev.of_node = pdev->dev.of_node; bs = spi_controller_get_devdata(ctlr); + bs->ctlr = ctlr; bs->regs = devm_platform_ioremap_resource(pdev, 0); if (IS_ERR(bs->regs)) { @@ -1344,7 +1346,7 @@ static int bcm2835_spi_probe(struct platform_device *pdev) BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX); err = devm_request_irq(&pdev->dev, bs->irq, bcm2835_spi_interrupt, 0, - dev_name(&pdev->dev), ctlr); + dev_name(&pdev->dev), bs); if (err) { dev_err(&pdev->dev, "could not request IRQ: %d\n", err); goto out_dma_release; -- 2.23.0.dirty
WARNING: multiple messages have this Message-ID (diff)
From: Robin Murphy <robin.murphy@arm.com> To: broonie@kernel.org, nsaenzjulienne@suse.de, f.fainelli@gmail.com, rjui@broadcom.com, sbranden@broadcom.com Cc: linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org, lukas@wunner.de, bcm-kernel-feedback-list@broadcom.com, linux-rpi-kernel@lists.infradead.org, kernel@martin.sperl.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH 2/3] spi: bcm2835: Micro-optimise IRQ handler Date: Tue, 16 Jun 2020 01:09:28 +0100 [thread overview] Message-ID: <6b401cb521539caffab21f05b4c8cba6c9d27c6e.1592261248.git.robin.murphy@arm.com> (raw) In-Reply-To: <cover.1592261248.git.robin.murphy@arm.com> The IRQ handler only needs the struct spi_controller for the sake of the completion at the end of a transfer. Passing the struct bcm2835_spi directly as the IRQ data allows that level of indirection to be pushed into the completion path for the reverse lookup, and avoided entirely in all other cases. This saves one explicit load in the critical path, plus (for a GCC 8.3 build) two registers worth of stack frame overhead. Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- drivers/spi/spi-bcm2835.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c index 524a91e52111..aec70ac8911e 100644 --- a/drivers/spi/spi-bcm2835.c +++ b/drivers/spi/spi-bcm2835.c @@ -86,6 +86,7 @@ MODULE_PARM_DESC(polling_limit_us, * @clk: core clock, divided to calculate serial clock * @irq: interrupt, signals TX FIFO empty or RX FIFO ¾ full * @tfr: SPI transfer currently processed + * @ctlr: SPI controller reverse lookup * @tx_buf: pointer whence next transmitted byte is read * @rx_buf: pointer where next received byte is written * @tx_len: remaining bytes to transmit @@ -125,6 +126,7 @@ struct bcm2835_spi { struct clk *clk; int irq; struct spi_transfer *tfr; + struct spi_controller *ctlr; const u8 *tx_buf; u8 *rx_buf; int tx_len; @@ -362,8 +364,7 @@ static void bcm2835_spi_reset_hw(struct bcm2835_spi *bs) static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id) { - struct spi_controller *ctlr = dev_id; - struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr); + struct bcm2835_spi *bs = dev_id; u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS); /* @@ -387,7 +388,7 @@ static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id) /* Transfer complete - reset SPI HW */ bcm2835_spi_reset_hw(bs); /* wake up the framework */ - complete(&ctlr->xfer_completion); + complete(&bs->ctlr->xfer_completion); } return IRQ_HANDLED; @@ -1310,6 +1311,7 @@ static int bcm2835_spi_probe(struct platform_device *pdev) ctlr->dev.of_node = pdev->dev.of_node; bs = spi_controller_get_devdata(ctlr); + bs->ctlr = ctlr; bs->regs = devm_platform_ioremap_resource(pdev, 0); if (IS_ERR(bs->regs)) { @@ -1344,7 +1346,7 @@ static int bcm2835_spi_probe(struct platform_device *pdev) BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX); err = devm_request_irq(&pdev->dev, bs->irq, bcm2835_spi_interrupt, 0, - dev_name(&pdev->dev), ctlr); + dev_name(&pdev->dev), bs); if (err) { dev_err(&pdev->dev, "could not request IRQ: %d\n", err); goto out_dma_release; -- 2.23.0.dirty _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-06-16 0:09 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-06-16 0:09 [PATCH 0/3] spi: bcm2835: Interrupt-handling optimisations Robin Murphy 2020-06-16 0:09 ` Robin Murphy 2020-06-16 0:09 ` [PATCH 1/3] spi: bcm3835: Tidy up bcm2835_spi_reset_hw() Robin Murphy 2020-06-16 0:09 ` Robin Murphy 2020-06-16 0:09 ` Robin Murphy [this message] 2020-06-16 0:09 ` [PATCH 2/3] spi: bcm2835: Micro-optimise IRQ handler Robin Murphy 2020-06-16 0:09 ` [PATCH 3/3] spi: bcm2835: Micro-optimise FIFO loops Robin Murphy 2020-06-16 0:09 ` Robin Murphy 2020-07-01 22:24 ` [PATCH 0/3] spi: bcm2835: Interrupt-handling optimisations Mark Brown 2020-07-01 22:24 ` Mark Brown
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