linux-kernel - Re: [PATCH v4 07/10] i3c: master: Add driver for Cadence IP

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Date:   Mon, 4 Jun 2018 13:26:15 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Przemyslaw Gaj <pgaj@...ence.com>
Cc:     Wolfram Sang <wsa@...-dreams.de>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        Jonathan Corbet <corbet@....net>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Przemyslaw Sroka <psroka@...ence.com>,
        Arkadiusz Golec <agolec@...ence.com>,
        Alan Douglas <adouglas@...ence.com>,
        Bartosz Folta <bfolta@...ence.com>,
        Damian Kos <dkos@...ence.com>,
        Alicja Jurasik-Urbaniak <alicja@...ence.com>,
        Cyprian Wronka <cwronka@...ence.com>,
        Suresh Punnoose <sureshp@...ence.com>,
        Rafal Ciepiela <rafalc@...ence.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Nishanth Menon <nm@...com>, Rob Herring <robh+dt@...nel.org>,
        Pawel Moll <pawel.moll@....com>,
        Mark Rutland <mark.rutland@....com>,
        Ian Campbell <ijc+devicetree@...lion.org.uk>,
        Kumar Gala <galak@...eaurora.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Vitor Soares <Vitor.Soares@...opsys.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Xiang Lin <Xiang.Lin@...aptics.com>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH v4 07/10] i3c: master: Add driver for Cadence IP

Hi Przemek,

On Mon, 4 Jun 2018 09:24:51 +0000
Przemyslaw Gaj <pgaj@...ence.com> wrote:

> Hi Boris,
> 
> Few things regarding Cadence IP driver:
> 
> On 6/4/18, 9:31 AM, "Boris Brezillon" <boris.brezillon@...tlin.com> wrote:
> 
>     +static void cdns_i3c_master_handle_ibi(struct cdns_i3c_master *master,
>     +				       u32 ibir)
>     +{
>     +	struct cdns_i3c_i2c_dev_data *data;
>     +	bool data_consumed = false;
>     +	struct i3c_ibi_slot *slot;
>     +	u32 id = IBIR_SLVID(ibir);
>     +	struct i3c_device *dev;
>     +	int len, i, j;
>     +	u8 *buf;
>     +
>     +	/*
>     +	 * FIXME: maybe we should report the FIFO OVF errors to the upper
>     +	 * layer.
>     +	 */
>     +	if (id >= master->ibi.num_slots || (ibir & IBIR_ERROR))
>     +		goto out;
>     +
>     +	dev = master->ibi.slots[id];
>     +	spin_lock(&master->ibi.lock);
>     +
>     +	data = i3c_device_get_master_data(dev);
>     +	slot = i3c_generic_ibi_get_free_slot(data->ibi_pool);
>     +	if (!slot)
>     +		goto out_unlock;
>     +
>     +	buf = slot->data;
>     +
>     +	len = IBIR_XFER_BYTES(ibir);
>     +	for (i = 0; i < IBIR_XFER_BYTES(ibir); i += 4) {
>     +		u32 tmp = readl(master->regs + IBI_DATA_FIFO);
>     +
>     +		for (j = 0; j < 4 && i + j < dev->ibi->max_payload_len; j++)
>     +			buf[i + j] = tmp >> (j * 8);
>     +
>     +	}
>     +	slot->len = min_t(unsigned int, IBIR_XFER_BYTES(ibir),
>     +			  dev->ibi->max_payload_len);
>     +	i3c_master_queue_ibi(dev, slot);
>     +	data_consumed = true;
>     +
>     +out_unlock:
>     +	spin_unlock(&master->ibi.lock);
>     +
>     +out:
>     +	/* Consume data from the FIFO if it's not been done already. */
>     +	if (!data_consumed) {
>     +		for (i = 0; i < IBIR_XFER_BYTES(ibir); i += 4)
>     +			readl(master->regs + IBI_DATA_FIFO);
>     +	}
>     +}
>     
> len variable is unneeded.

Will get rid of len.

>     +
>     +	/* Device ID0 is reserved to describe this master. */
>     +	master->maxdevs = CONF_STATUS0_DEVS_NUM(val);
>     +	master->free_rr_slots = GENMASK(master->maxdevs, 1);
>     +
>     +	val = readl(master->regs + CONF_STATUS1);
>     +	master->caps.cmdfifodepth = CONF_STATUS1_CMD_DEPTH(val);
>     +	master->caps.rxfifodepth = CONF_STATUS1_RX_DEPTH(val);
>     +	master->caps.txfifodepth = CONF_STATUS1_TX_DEPTH(val);
>     +	master->caps.ibirfifodepth = 16;
> 
> IBI fifo depth is hardcoded. You can read this value from CONF_STATUS0 register.
> 
>     +	master->caps.cmdrfifodepth = 16;
> 
> CMDR fifo depth is hardcoded. You can read this value from CONF_STATUS0 register also.

Sure, I'll use the FIFO depth exposed in CONF_STATUS0.

Thanks,

Boris