Return-path: Received: from mail-bw0-f169.google.com ([209.85.218.169]:53834 "EHLO mail-bw0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755545AbZDEVEP (ORCPT ); Sun, 5 Apr 2009 17:04:15 -0400 Received: by bwz17 with SMTP id 17so1627594bwz.37 for ; Sun, 05 Apr 2009 14:04:12 -0700 (PDT) From: Max Filippov To: linux-wireless@vger.kernel.org Cc: Christian Lamparter , Max Filippov Subject: [PATCH] p54spi: get rid of busy-wait loops Date: Mon, 6 Apr 2009 01:03:09 +0400 Message-Id: <1238965389-5706-1-git-send-email-jcmvbkbc@gmail.com> (sfid-20090405_230419_047866_3E0935F0) In-Reply-To: <> References: <> Sender: linux-wireless-owner@vger.kernel.org List-ID: p54spi_wakeup and p54spi_tx_frame used busy-waiting loop to poll for 'ready' bits in SPI_ADRS_HOST_INTERRUPTS register. With this change in place 'WR_READY timeout' messages do not show anymore. Signed-off-by: Max Filippov --- I wish I knew for sure why. My guess is that busy-waiting somehow interferes with SPI transfer scheduling. drivers/net/wireless/p54/p54spi.c | 41 ++++++++++++------------------------ 1 files changed, 14 insertions(+), 27 deletions(-) diff --git a/drivers/net/wireless/p54/p54spi.c b/drivers/net/wireless/p54/p54spi.c index 2903672..e4e708e 100644 --- a/drivers/net/wireless/p54/p54spi.c +++ b/drivers/net/wireless/p54/p54spi.c @@ -153,14 +153,13 @@ static const struct p54spi_spi_reg p54spi_registers_array[] = static int p54spi_wait_bit(struct p54s_priv *priv, u16 reg, __le32 bits) { int i; - __le32 buffer; for (i = 0; i < 2000; i++) { - p54spi_spi_read(priv, reg, &buffer, sizeof(buffer)); + __le32 buffer = p54spi_read32(priv, reg); if ((buffer & bits) == bits) return 1; - msleep(1); + msleep(0); } return 0; } @@ -171,10 +170,10 @@ static int p54spi_spi_write_dma(struct p54s_priv *priv, __le32 base, p54spi_write16(priv, SPI_ADRS_DMA_WRITE_CTRL, cpu_to_le16(SPI_DMA_WRITE_CTRL_ENABLE)); - if (p54spi_wait_bit(priv, SPI_ADRS_DMA_WRITE_CTRL, - cpu_to_le32(HOST_ALLOWED)) == 0) { + if (!p54spi_wait_bit(priv, SPI_ADRS_DMA_WRITE_CTRL, + cpu_to_le32(HOST_ALLOWED))) { dev_err(&priv->spi->dev, "spi_write_dma not allowed " - "to DMA write."); + "to DMA write.\n"); return -EAGAIN; } @@ -316,21 +315,15 @@ static inline void p54spi_int_ack(struct p54s_priv *priv, u32 val) static void p54spi_wakeup(struct p54s_priv *priv) { - unsigned long timeout; - u32 ints; - /* wake the chip */ p54spi_write32(priv, SPI_ADRS_ARM_INTERRUPTS, cpu_to_le32(SPI_TARGET_INT_WAKEUP)); /* And wait for the READY interrupt */ - timeout = jiffies + HZ; - - ints = p54spi_read32(priv, SPI_ADRS_HOST_INTERRUPTS); - while (!(ints & SPI_HOST_INT_READY)) { - if (time_after(jiffies, timeout)) - goto out; - ints = p54spi_read32(priv, SPI_ADRS_HOST_INTERRUPTS); + if (!p54spi_wait_bit(priv, SPI_ADRS_HOST_INTERRUPTS, + cpu_to_le32(SPI_HOST_INT_READY))) { + dev_err(&priv->spi->dev, "INT_READY timeout\n"); + goto out; } p54spi_int_ack(priv, SPI_HOST_INT_READY); @@ -418,9 +411,7 @@ static irqreturn_t p54spi_interrupt(int irq, void *config) static int p54spi_tx_frame(struct p54s_priv *priv, struct sk_buff *skb) { struct p54_hdr *hdr = (struct p54_hdr *) skb->data; - unsigned long timeout; int ret = 0; - u32 ints; p54spi_wakeup(priv); @@ -428,15 +419,11 @@ static int p54spi_tx_frame(struct p54s_priv *priv, struct sk_buff *skb) if (ret < 0) goto out; - timeout = jiffies + 2 * HZ; - ints = p54spi_read32(priv, SPI_ADRS_HOST_INTERRUPTS); - while (!(ints & SPI_HOST_INT_WR_READY)) { - if (time_after(jiffies, timeout)) { - dev_err(&priv->spi->dev, "WR_READY timeout\n"); - ret = -1; - goto out; - } - ints = p54spi_read32(priv, SPI_ADRS_HOST_INTERRUPTS); + if (!p54spi_wait_bit(priv, SPI_ADRS_HOST_INTERRUPTS, + cpu_to_le32(SPI_HOST_INT_WR_READY))) { + dev_err(&priv->spi->dev, "WR_READY timeout\n"); + ret = -1; + goto out; } p54spi_int_ack(priv, SPI_HOST_INT_WR_READY); -- 1.5.4.3