From patchwork Wed Nov 18 16:20:06 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Torsten Fleischer X-Patchwork-Id: 38761 X-Patchwork-Delegate: grant.likely@secretlab.ca Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from bilbo.ozlabs.org (localhost [127.0.0.1]) by ozlabs.org (Postfix) with ESMTP id 765D4B7C7C for ; Thu, 19 Nov 2009 03:36:55 +1100 (EST) X-Greylist: delayed 973 seconds by postgrey-1.32 at bilbo; Thu, 19 Nov 2009 03:36:45 EST Received: from mailout07.t-online.de (mailout07.t-online.de [194.25.134.83]) by ozlabs.org (Postfix) with ESMTP id 8F3C0B7B9C for ; Thu, 19 Nov 2009 03:36:45 +1100 (EST) Received: from fwd01.aul.t-online.de by mailout07.t-online.de with smtp id 1NAnGU-0007hR-03; Wed, 18 Nov 2009 17:20:18 +0100 Received: from linux-z6s0.localnet (Sm1EkMZUwhnihFBoGddRh9EGD30lPXUZ3SFGCcq3ZbQvJ3p88jxuO65ZGUy605agc5@[87.163.93.208]) by fwd01.t-online.de with esmtp id 1NAnGJ-1gj9qi0; Wed, 18 Nov 2009 17:20:07 +0100 From: Torsten Fleischer Organization: privat To: avorontsov@ru.mvista.com Subject: Re: spi_mpc8xxx.c: chip select polarity problem Date: Wed, 18 Nov 2009 17:20:06 +0100 User-Agent: KMail/1.12.2 (Linux/2.6.31.5-0.1-default; KDE/4.3.1; i686; ; ) References: <200911161742.46663.to-fleischer@t-online.de> <20091117202211.GB27574@oksana.dev.rtsoft.ru> <20091117232823.GA19058@oksana.dev.rtsoft.ru> In-Reply-To: <20091117232823.GA19058@oksana.dev.rtsoft.ru> MIME-Version: 1.0 Message-Id: <200911181720.06390.to-fleischer@t-online.de> X-ID: Sm1EkMZUwhnihFBoGddRh9EGD30lPXUZ3SFGCcq3ZbQvJ3p88jxuO65ZGUy605agc5 X-TOI-MSGID: 7a105c31-9fd5-4f13-b6b3-6c646cfdb428 Cc: linuxppc-dev@lists.ozlabs.org X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org On Wen, Nov 18, 2009 00:28:23 Anton Vorontsov wrote: [...] > > > > > So it might be better to fix up initial value in the platform code? > > > > > > > > Oh, we actually cannot, because the driver calls > > > > gpio_direction_output(). > > > > > > > > And since we don't know the mode prior to SPI device's driver > > > > probe() finished, we'll have to set up an initial state in the > > > > first SPI transfer. I.e. something like this: > > > > > > In most cases the device drivers perform SPI transfers already in their > > > probe() function. How can it be ensured that the CS of all other > > > devices are inactive even if they are not initialized at that time? > > > > Good question. Oh, well... then we have to use spi-cs-high, > > no matter that it is a duplication of the 'compatible' property. > > SPI bus drivers don't know all the devices and their CS level, > > and so spi-cs-high is the only way to tell that information. :-( > > Oh. On the other hand, we can postpone the gpio_direction_output() > call, and still require that the platform code (or firmware) > should be responsible for setting a sane default values on the > chip selects. > How about that? diff -u -r -N linux-2.6.31.6_orig//drivers/spi/spi_mpc8xxx.c linux-2.6.31.6/drivers/spi/spi_mpc8xxx.c --- linux-2.6.31.6_orig//drivers/spi/spi_mpc8xxx.c 2009-11-10 01:32:31.000000000 +0100 +++ linux-2.6.31.6/drivers/spi/spi_mpc8xxx.c 2009-11-18 10:47:06.000000000 +0100 @@ -114,6 +114,7 @@ u32 rx_shift; /* RX data reg shift when in qe mode */ u32 tx_shift; /* TX data reg shift when in qe mode */ u32 hw_mode; /* Holds HW mode register settings */ + int initialized; }; static inline void mpc8xxx_spi_write_reg(__be32 __iomem *reg, u32 val) @@ -437,6 +438,7 @@ cs = kzalloc(sizeof *cs, GFP_KERNEL); if (!cs) return -ENOMEM; + cs->initialized = 0; spi->controller_state = cs; } mpc8xxx_spi = spi_master_get_devdata(spi->master); @@ -503,15 +505,25 @@ return ret; } + +static void mpc8xxx_spi_cs_init(struct spi_device *spi); + + static int mpc8xxx_spi_transfer(struct spi_device *spi, struct spi_message *m) { struct mpc8xxx_spi *mpc8xxx_spi = spi_master_get_devdata(spi->master); + struct spi_mpc8xxx_cs *cs = spi->controller_state; unsigned long flags; m->actual_length = 0; m->status = -EINPROGRESS; + if (cs && !cs->initialized) { + mpc8xxx_spi_cs_init(spi); + cs->initialized = 1; + } + spin_lock_irqsave(&mpc8xxx_spi->lock, flags); list_add_tail(&m->queue, &mpc8xxx_spi->queue); queue_work(mpc8xxx_spi->workqueue, &mpc8xxx_spi->work); @@ -671,6 +683,17 @@ gpio_set_value(gpio, on ^ alow); } +static void mpc8xxx_spi_cs_init(struct spi_device *spi) +{ + struct device *dev = spi->dev.parent; + struct mpc8xxx_spi_probe_info *pinfo = to_of_pinfo(dev->platform_data); + u16 cs = spi->chip_select; + int gpio = pinfo->gpios[cs]; + bool on = (pinfo->alow_flags[cs] ^ !(spi->mode & SPI_CS_HIGH)); + + gpio_direction_output(gpio, on); +} + static int of_mpc8xxx_spi_get_chipselects(struct device *dev) { struct device_node *np = dev_archdata_get_node(&dev->archdata); @@ -720,14 +743,6 @@ pinfo->gpios[i] = gpio; pinfo->alow_flags[i] = flags & OF_GPIO_ACTIVE_LOW; - - ret = gpio_direction_output(pinfo->gpios[i], - pinfo->alow_flags[i]); - if (ret) { - dev_err(dev, "can't set output direction for gpio " - "#%d: %d\n", i, ret); - goto err_loop; - } } pdata->max_chipselect = ngpios;