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Sun, 29 Mar 2020 21:13:15 +0000 From: To: , , , , Subject: Re: [PATCH v4 1/4] i2c: at91: Send bus clear command if SDA is down Thread-Topic: [PATCH v4 1/4] i2c: at91: Send bus clear command if SDA is down Thread-Index: AQHV6/NVDTMXDOPubUuDjXQVQvQtIqhgRdwA Date: Sun, 29 Mar 2020 21:13:15 +0000 Message-ID: <3ebaa9a6-73d5-863f-bc40-e38230ab732e@microchip.com> References: <20200225155012.22764-1-codrin.ciubotariu@microchip.com> In-Reply-To: <20200225155012.22764-1-codrin.ciubotariu@microchip.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 authentication-results: spf=none (sender IP is ) smtp.mailfrom=Ludovic.Desroches@microchip.com; x-originating-ip: [92.150.97.227] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 67654b6d-81fe-4125-b6d3-08d7d425ff0a x-ms-traffictypediagnostic: DM6PR11MB4753: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-bypassexternaltag: True x-ms-oob-tlc-oobclassifiers: OLM:10000; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2/25/2020 4:50 PM, Codrin Ciubotariu wrote: > After a transfer timeout, some faulty I2C slave devices might hold down > the SDA pin. We can generate a bus clear command, hoping that the slave > might release the pins. > If the CLEAR command is not supported, we will use gpio recovery, if > available, to reset the bus. > > Signed-off-by: Codrin Ciubotariu Sounds good so Acked-by: Ludovic Desroches Wolfram, you have accepted the v3 of the recovery support and requested these changes. It has been sent as a v4, but, in fact, this patch goes on top on v3. It could, should, have been a new patch. Regards Ludovic > --- > > Changes in v4: > - moved the HW bus clear command in a recover_bus() function, to be able > to just call i2c_recover_bus() if a transfer fails; > - recovery gpios are no longer taken if HW bus clear command is > supported; > > Changes in v3: > - removed unnecessary condition from info print; > - removed unneded declarations; > > Changes in v2: > - called i2c_recover_bus() after an error occurs, if SDA is down; > - release gpios if recovery information is incomplete; > > drivers/i2c/busses/i2c-at91-core.c | 2 ++ > drivers/i2c/busses/i2c-at91-master.c | 49 ++++++++++++++++++++++++---- > drivers/i2c/busses/i2c-at91.h | 7 +++- > 3 files changed, 50 insertions(+), 8 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-at91-core.c b/drivers/i2c/busses/i2c-at91-core.c > index 3da1a8acecb5..e14edd236108 100644 > --- a/drivers/i2c/busses/i2c-at91-core.c > +++ b/drivers/i2c/busses/i2c-at91-core.c > @@ -131,6 +131,7 @@ static struct at91_twi_pdata sama5d2_config = { > .has_dig_filtr = true, > .has_adv_dig_filtr = true, > .has_ana_filtr = true, > + .has_clear_cmd = false, /* due to errata, CLEAR cmd is not working */ > }; > > static struct at91_twi_pdata sam9x60_config = { > @@ -142,6 +143,7 @@ static struct at91_twi_pdata sam9x60_config = { > .has_dig_filtr = true, > .has_adv_dig_filtr = true, > .has_ana_filtr = true, > + .has_clear_cmd = true, > }; > > static const struct of_device_id atmel_twi_dt_ids[] = { > diff --git a/drivers/i2c/busses/i2c-at91-master.c b/drivers/i2c/busses/i2c-at91-master.c > index 0aba51a7df32..776e95962ab6 100644 > --- a/drivers/i2c/busses/i2c-at91-master.c > +++ b/drivers/i2c/busses/i2c-at91-master.c > @@ -480,7 +480,6 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) > unsigned long time_left; > bool has_unre_flag = dev->pdata->has_unre_flag; > bool has_alt_cmd = dev->pdata->has_alt_cmd; > - struct i2c_bus_recovery_info *rinfo = &dev->rinfo; > > /* > * WARNING: the TXCOMP bit in the Status Register is NOT a clear on > @@ -641,11 +640,12 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) > AT91_TWI_THRCLR | AT91_TWI_LOCKCLR); > } > > - if (rinfo->get_sda && !(rinfo->get_sda(&dev->adapter))) { > - dev_dbg(dev->dev, > - "SDA is down; clear bus using gpio\n"); > - i2c_recover_bus(&dev->adapter); > - } > + /* > + * some faulty I2C slave devices might hold SDA down; > + * we can send a bus clear command, hoping that the pins will be > + * released > + */ > + i2c_recover_bus(&dev->adapter); > > return ret; > } > @@ -830,7 +830,7 @@ static void at91_unprepare_twi_recovery(struct i2c_adapter *adap) > pinctrl_select_state(dev->pinctrl, dev->pinctrl_pins_default); > } > > -static int at91_init_twi_recovery_info(struct platform_device *pdev, > +static int at91_init_twi_recovery_gpio(struct platform_device *pdev, > struct at91_twi_dev *dev) > { > struct i2c_bus_recovery_info *rinfo = &dev->rinfo; > @@ -880,6 +880,41 @@ static int at91_init_twi_recovery_info(struct platform_device *pdev, > return 0; > } > > +static int at91_twi_recover_bus_cmd(struct i2c_adapter *adap) > +{ > + struct at91_twi_dev *dev = i2c_get_adapdata(adap); > + > + dev->transfer_status |= at91_twi_read(dev, AT91_TWI_SR); > + if (!(dev->transfer_status & AT91_TWI_SDA)) { > + dev_dbg(dev->dev, "SDA is down; sending bus clear command\n"); > + if (dev->use_alt_cmd) { > + unsigned int acr; > + > + acr = at91_twi_read(dev, AT91_TWI_ACR); > + acr &= ~AT91_TWI_ACR_DATAL_MASK; > + at91_twi_write(dev, AT91_TWI_ACR, acr); > + } > + at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_CLEAR); > + } > + > + return 0; > +} > + > +static int at91_init_twi_recovery_info(struct platform_device *pdev, > + struct at91_twi_dev *dev) > +{ > + struct i2c_bus_recovery_info *rinfo = &dev->rinfo; > + bool has_clear_cmd = dev->pdata->has_clear_cmd; > + > + if (!has_clear_cmd) > + return at91_init_twi_recovery_gpio(pdev, dev); > + > + rinfo->recover_bus = at91_twi_recover_bus_cmd; > + dev->adapter.bus_recovery_info = rinfo; > + > + return 0; > +} > + > int at91_twi_probe_master(struct platform_device *pdev, > u32 phy_addr, struct at91_twi_dev *dev) > { > diff --git a/drivers/i2c/busses/i2c-at91.h b/drivers/i2c/busses/i2c-at91.h > index f57a6cab96b4..7e7b4955ca7f 100644 > --- a/drivers/i2c/busses/i2c-at91.h > +++ b/drivers/i2c/busses/i2c-at91.h > @@ -36,6 +36,7 @@ > #define AT91_TWI_SVDIS BIT(5) /* Slave Transfer Disable */ > #define AT91_TWI_QUICK BIT(6) /* SMBus quick command */ > #define AT91_TWI_SWRST BIT(7) /* Software Reset */ > +#define AT91_TWI_CLEAR BIT(15) /* Bus clear command */ > #define AT91_TWI_ACMEN BIT(16) /* Alternative Command Mode Enable */ > #define AT91_TWI_ACMDIS BIT(17) /* Alternative Command Mode Disable */ > #define AT91_TWI_THRCLR BIT(24) /* Transmit Holding Register Clear */ > @@ -69,6 +70,8 @@ > #define AT91_TWI_NACK BIT(8) /* Not Acknowledged */ > #define AT91_TWI_EOSACC BIT(11) /* End Of Slave Access */ > #define AT91_TWI_LOCK BIT(23) /* TWI Lock due to Frame Errors */ > +#define AT91_TWI_SCL BIT(24) /* TWI SCL status */ > +#define AT91_TWI_SDA BIT(25) /* TWI SDA status */ > > #define AT91_TWI_INT_MASK \ > (AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK \ > @@ -81,7 +84,8 @@ > #define AT91_TWI_THR 0x0034 /* Transmit Holding Register */ > > #define AT91_TWI_ACR 0x0040 /* Alternative Command Register */ > -#define AT91_TWI_ACR_DATAL(len) ((len) & 0xff) > +#define AT91_TWI_ACR_DATAL_MASK GENMASK(15, 0) > +#define AT91_TWI_ACR_DATAL(len) ((len) & AT91_TWI_ACR_DATAL_MASK) > #define AT91_TWI_ACR_DIR BIT(8) > > #define AT91_TWI_FILTR 0x0044 > @@ -118,6 +122,7 @@ struct at91_twi_pdata { > bool has_dig_filtr; > bool has_adv_dig_filtr; > bool has_ana_filtr; > + bool has_clear_cmd; > struct at_dma_slave dma_slave; > }; > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel