Messages in this thread | | | Date | Sat, 2 Dec 2023 13:01:42 +0100 | Subject | Re: [PATCH v3 1/5] w1: ds2490: support block sizes larger than 128 bytes in ds_read_block | From | Krzysztof Kozlowski <> |
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On 30/11/2023 14:52, marc.ferland@gmail.com wrote: > From: Marc Ferland <marc.ferland@sonatest.com> > > The current ds_read_block function only supports block sizes up to > 128 bytes, which is the depth of the 'data out' fifo on the ds2490. > > Reading larger blocks will fail with a: -110 (ETIMEDOUT) from > usb_control_msg(). Example: > > $ dd if=/sys/bus/w1/devices/43-000000478756/eeprom bs=256 count=1 > > yields to the following message from the kernel: > > usb 5-1: Failed to write 1-wire data to ep0x2: err=-110. > > I discovered this issue while implementing support for the ds28ec20 > eeprom in the w1-2433 driver. This driver accepts reading blocks of > sizes up to the size of the entire memory (2560 bytes in the case of > the ds28ec20). Note that this issue _does not_ arises when the kernel > is configured with CONFIG_W1_SLAVE_DS2433_CRC enabled since in this > mode the driver reads one 32 byte block at a time (a single memory > page). > > Also, from the ds2490 datasheet (2995.pdf, page 22, BLOCK I/O > command): > > For a block write sequence the EP2 FIFO must be pre-filled with > data before command execution. Additionally, for block sizes > greater then the FIFO size, the FIFO content status must be > monitored by host SW so that additional data can be sent to the > FIFO when necessary. A similar EP3 FIFO content monitoring > requirement exists for block read sequences. During a block read > the number of bytes loaded into the EP3 FIFO must be monitored so > that the data can be read before the FIFO overflows. > > Breaking the buffer in 128 bytes blocks and simply calling the > original code sequence has solved the issue for me. > > Tested with a DS1490F usb<->one-wire adapter and both the DS28EC20 and > DS2433 eeprom memories. > > Note: The v1 of this patch changed both the ds_read_block and > ds_write_block functions, but since I don't have any way to test the > 'write' part with writes bigger than a page size (maximum accepted by > my eeprom), I preferred not to make any assumptions and I just > removed that part.
Drop that paragraph, not really helping to understand the commit once accepted.
> > Signed-off-by: Marc Ferland <marc.ferland@sonatest.com> > --- > drivers/w1/masters/ds2490.c | 25 +++++++++++++++++++++---- > 1 file changed, 21 insertions(+), 4 deletions(-) > > diff --git a/drivers/w1/masters/ds2490.c b/drivers/w1/masters/ds2490.c > index 5f5b97e24700..b6e244992c15 100644 > --- a/drivers/w1/masters/ds2490.c > +++ b/drivers/w1/masters/ds2490.c > @@ -98,6 +98,8 @@ > #define ST_EPOF 0x80 > /* Status transfer size, 16 bytes status, 16 byte result flags */ > #define ST_SIZE 0x20 > +/* 1-wire data i/o fifo size, 128 bytes */ > +#define FIFO_SIZE 0x80 > > /* Result Register flags */ > #define RR_DETECT 0xA5 /* New device detected */ > @@ -614,14 +616,11 @@ static int ds_read_byte(struct ds_device *dev, u8 *byte) > return 0; > } > > -static int ds_read_block(struct ds_device *dev, u8 *buf, int len) > +static int __read_block(struct ds_device *dev, u8 *buf, int len)
Drop __ and name the function descriptive. It's confusing to have two times read_block(). Just name them according to what they really do.
Best regards, Krzysztof
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