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SubjectRe: [PATCH v5 09/19] mtd: spi-nor: sfdp: parse xSPI Profile 1.0 table
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Hi Pratyush,

> +/**
> + * spi_nor_parse_profile1() - parse the xSPI Profile 1.0 table
> + * @nor: pointer to a 'struct spi_nor'
> + * @param_header: pointer to the 'struct sfdp_parameter_header'
describing
> + * the 4-Byte Address Instruction Table length and version.
> + * @params: pointer to the 'struct spi_nor_flash_parameter' to be.
> + *
> + * Return: 0 on success, -errno otherwise.
> + */
> +static int spi_nor_parse_profile1(struct spi_nor *nor,
> + const struct sfdp_parameter_header *profile1_header,
> + struct spi_nor_flash_parameter *params)
> +{
> + u32 *table, opcode, addr;
> + size_t len;
> + int ret, i;
> +
> + len = profile1_header->length * sizeof(*table);
> + table = kmalloc(len, GFP_KERNEL);
> + if (!table)
> + return -ENOMEM;
> +
> + addr = SFDP_PARAM_HEADER_PTP(profile1_header);
> + ret = spi_nor_read_sfdp(nor, addr, len, table);
> + if (ret)
> + goto out;
> +
> + /* Fix endianness of the table DWORDs. */
> + for (i = 0; i < profile1_header->length; i++)
> + table[i] = le32_to_cpu(table[i]);
> +
> + /* Get 8D-8D-8D fast read opcode and dummy cycles. */
> + opcode = FIELD_GET(PROFILE1_DWORD1_RD_FAST_CMD, table[0]);
> +
> + /*
> + * Update the fast read settings. We set the default dummy cycles to
20
> + * here. Flashes can change this value if they need to when enabling
> + * octal mode.
> + */
> + spi_nor_set_read_settings(&params->reads[SNOR_CMD_READ_8_8_8_DTR],
> + 0, 20, opcode,
> + SNOR_PROTO_8_8_8_DTR);
> +


I thought we have a agreement that only do parse here, no other read
parameters setting.

Driver should get dummy cycles used for various frequencies
from 4th and 5th DWORD of xSPI table.[1]

[1]
https://patchwork.ozlabs.org/project/linux-mtd/patch/1587451187-6889-3-git-send-email-masonccyang@mxic.com.tw/


In addition, 20 dummy cycles is for 200MHz but not for 100MHz, 133MHz and
166MHz
in case of read performance concern.

Given a correct dummy cycles for a specific device. [2]

[2]
https://patchwork.ozlabs.org/project/linux-mtd/patch/1587451187-6889-5-git-send-email-masonccyang@mxic.com.tw/



> + /*
> + * Set the Read Status Register dummy cycles and dummy address
bytes.
> + */
> + if (table[0] & PROFILE1_DWORD1_RDSR_DUMMY)
> + params->rdsr_dummy = 8;
> + else
> + params->rdsr_dummy = 4;
> +
> + if (table[0] & PROFILE1_DWORD1_RDSR_ADDR_BYTES)
> + params->rdsr_addr_nbytes = 4;
> + else
> + params->rdsr_addr_nbytes = 0;
> +
> +out:
> + kfree(table);
> + return ret;
> +}
> +

thanks & best regards,
Mason


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CONFIDENTIALITY NOTE:

This e-mail and any attachments may contain confidential information and/or personal data, which is protected by applicable laws. Please be reminded that duplication, disclosure, distribution, or use of this e-mail (and/or its attachments) or any part thereof is prohibited. If you receive this e-mail in error, please notify us immediately and delete this mail as well as its attachment(s) from your system. In addition, please be informed that collection, processing, and/or use of personal data is prohibited unless expressly permitted by personal data protection laws. Thank you for your attention and cooperation.

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