Re: [PATCH 3/3] iio: temperature: ltc2983: support more parts

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On 10/14/22 18:44, Jonathan Cameron wrote:
On Fri, 14 Oct 2022 15:37:24 +0300
Cosmin Tanislav <demonsingur@xxxxxxxxx> wrote:

From: Cosmin Tanislav <cosmin.tanislav@xxxxxxxxxx>

Add support for the following parts:
  * LTC2984
  * LTC2986
  * LTM2985

The LTC2984 is a variant of the LTC2983 with EEPROM.
The LTC2986 is a variant of the LTC2983 with only 10 channels,
EEPROM and support for active analog temperature sensors.
The LTM2985 is software-compatible with the LTC2986.

Signed-off-by: Cosmin Tanislav <cosmin.tanislav@xxxxxxxxxx>

...

Hi Cosmin,

Looks good except, I think we are still in the position that
regmap for spi doesn't guarantee to bounce buffer the bulk accesses
(last time I checked it actually did do so, but before that it didn't
and there are obvious optimizations to take it back to not doing so -
IRC Mark Brown's answer was we shouldn't rely on it..)

Anyhow, the existing driver has instances of this so its no worse
but we should really clean those up.

Jonathan


I can submit another patch for it. Although I'm pretty sure that
SPI regmap implementation doesn't need DMA safe access for it,
as I checked when I wrote the code.


+static int ltc2983_eeprom_cmd(struct ltc2983_data *st, unsigned int cmd,
+			      unsigned int wait_time, unsigned int status_reg,
+			      unsigned long status_fail_mask)
+{
+	__be32 bval = cpu_to_be32(LTC2983_EEPROM_KEY);
+	unsigned long time;
+	unsigned int val;
+	int ret;
+
+	ret = regmap_bulk_write(st->regmap, LTC2983_EEPROM_KEY_REG, &bval,
+				sizeof(bval));

SPI device and I was clearly dozing on existing driver but normally
we avoid assuming that regmap will always use a bounce buffer for bulk
accessors. Hence this should be a DMA safe buffer.


+	if (ret)
+		return ret;
+
+	reinit_completion(&st->completion);
+
+	ret = regmap_write(st->regmap, LTC2983_STATUS_REG,
+			   LTC2983_STATUS_START(true) | cmd);
+	if (ret)
+		return ret;
+
+	time = wait_for_completion_timeout(&st->completion,
+					   msecs_to_jiffies(wait_time));
+	if (!time) {
+		dev_err(&st->spi->dev, "EEPROM command timed out\n");
+		return -ETIMEDOUT;
+	}
+
+	ret = regmap_read(st->regmap, status_reg, &val);
+	if (ret)
+		return ret;
+
+	if (val & status_fail_mask) {
+		dev_err(&st->spi->dev, "EEPROM command failed: 0x%02X\n", val);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+




[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]


  Powered by Linux