On Tue, Jun 8, 2021 at 5:40 PM Luben Tuikov <luben.tuikov@xxxxxxx> wrote:
>
> Consult the i2c_adapter.quirks table for
> the maximum read/write data length per bus
> transaction. Do not exceed this transaction
> limit.
>
> Cc: Jean Delvare <jdelvare@xxxxxxx>
> Cc: Alexander Deucher <Alexander.Deucher@xxxxxxx>
> Cc: Andrey Grodzovsky <Andrey.Grodzovsky@xxxxxxx>
> Cc: Lijo Lazar <Lijo.Lazar@xxxxxxx>
> Cc: Stanley Yang <Stanley.Yang@xxxxxxx>
> Cc: Hawking Zhang <Hawking.Zhang@xxxxxxx>
> Signed-off-by: Luben Tuikov <luben.tuikov@xxxxxxx>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c | 80 +++++++++++++++++-----
> 1 file changed, 64 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c
> index 7fdb5bd2fc8bc8..94aeda1c7f8ca0 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c
> @@ -32,20 +32,9 @@
>
> #define EEPROM_OFFSET_SIZE 2
>
> -/**
> - * amdgpu_eeprom_xfer -- Read/write from/to an I2C EEPROM device
> - * @i2c_adap: pointer to the I2C adapter to use
> - * @slave_addr: I2C address of the slave device
> - * @eeprom_addr: EEPROM address from which to read/write
> - * @eeprom_buf: pointer to data buffer to read into/write from
> - * @buf_size: the size of @eeprom_buf
> - * @read: True if reading from the EEPROM, false if writing
> - *
> - * Returns the number of bytes read/written; -errno on error.
> - */
> -int amdgpu_eeprom_xfer(struct i2c_adapter *i2c_adap,
> - u16 slave_addr, u16 eeprom_addr,
> - u8 *eeprom_buf, u16 buf_size, bool read)
> +static int __amdgpu_eeprom_xfer(struct i2c_adapter *i2c_adap,
> + u16 slave_addr, u16 eeprom_addr,
> + u8 *eeprom_buf, u16 buf_size, bool read)
> {
> u8 eeprom_offset_buf[EEPROM_OFFSET_SIZE];
> struct i2c_msg msgs[] = {
> @@ -65,8 +54,8 @@ int amdgpu_eeprom_xfer(struct i2c_adapter *i2c_adap,
> u16 len;
>
> r = 0;
> - for (len = 0; buf_size > 0;
> - buf_size -= len, eeprom_addr += len, eeprom_buf += len) {
> + for ( ; buf_size > 0;
> + buf_size -= len, eeprom_addr += len, eeprom_buf += len) {
> /* Set the EEPROM address we want to write to/read from.
> */
> msgs[0].buf[0] = (eeprom_addr >> 8) & 0xff;
> @@ -120,3 +109,62 @@ int amdgpu_eeprom_xfer(struct i2c_adapter *i2c_adap,
>
> return r < 0 ? r : eeprom_buf - p;
> }
> +
> +/**
> + * amdgpu_eeprom_xfer -- Read/write from/to an I2C EEPROM device
> + * @i2c_adap: pointer to the I2C adapter to use
> + * @slave_addr: I2C address of the slave device
> + * @eeprom_addr: EEPROM address from which to read/write
> + * @eeprom_buf: pointer to data buffer to read into/write from
> + * @buf_size: the size of @eeprom_buf
> + * @read: True if reading from the EEPROM, false if writing
> + *
> + * Returns the number of bytes read/written; -errno on error.
> + */
> +int amdgpu_eeprom_xfer(struct i2c_adapter *i2c_adap,
> + u16 slave_addr, u16 eeprom_addr,
> + u8 *eeprom_buf, u16 buf_size, bool read)
> +{
> + const struct i2c_adapter_quirks *quirks = i2c_adap->quirks;
> + u16 limit;
> +
> + if (!quirks)
> + limit = 0;
> + else if (read)
> + limit = quirks->max_read_len;
> + else
> + limit = quirks->max_write_len;
> +
> + if (limit == 0) {
> + return __amdgpu_eeprom_xfer(i2c_adap, slave_addr, eeprom_addr,
> + eeprom_buf, buf_size, read);
> + } else if (limit <= EEPROM_OFFSET_SIZE) {
> + dev_err_ratelimited(&i2c_adap->dev,
> + "maddr:0x%04X size:0x%02X:quirk max_%s_len must be > %d",
> + eeprom_addr, buf_size,
> + read ? "read" : "write", EEPROM_OFFSET_SIZE);
> + return -EINVAL;
I presume we handle this case properly at higher levels (i.e., split
up EEPROM updates into smaller transactions)?
Alex
> + } else {
> + u16 ps; /* Partial size */
> + int res = 0, r;
> +
> + /* The "limit" includes all data bytes sent/received,
> + * which would include the EEPROM_OFFSET_SIZE bytes.
> + * Account for them here.
> + */
> + limit -= EEPROM_OFFSET_SIZE;
> + for ( ; buf_size > 0;
> + buf_size -= ps, eeprom_addr += ps, eeprom_buf += ps) {
> + ps = min(limit, buf_size);
> +
> + r = __amdgpu_eeprom_xfer(i2c_adap,
> + slave_addr, eeprom_addr,
> + eeprom_buf, ps, read);
> + if (r < 0)
> + return r;
> + res += r;
> + }
> +
> + return res;
> + }
> +}
> --
> 2.32.0
>
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