Commit 1cc577e6 authored by Ram Kumar Dwivedi's avatar Ram Kumar Dwivedi Committed by Martin K. Petersen
Browse files

scsi: ufs: pltfrm: Add DT support to limit HS gear and gear rate 



Introduce parsing of 'limit-hs-gear' and 'limit-gear-rate' device tree
properties to restrict high-speed gear and rate during initialization.

This is useful in cases where the customer board may have signal
integrity, clock configuration or layout issues that prevent reliable
operation at higher gears. Such limitations are especially critical in
those platforms, where stability is prioritized over peak performance.

Co-developed-by: default avatarNitin Rawat <quic_nitirawa@quicinc.com>
Signed-off-by: default avatarNitin Rawat <quic_nitirawa@quicinc.com>
Signed-off-by: default avatarRam Kumar Dwivedi <quic_rdwivedi@quicinc.com>
Reviewed-by: default avatarAlim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent d471a075

drivers/ufs/host/ufshcd-pltfrm.c

+33 −0
Original line number Diff line number Diff line
@@ -430,6 +430,39 @@ int ufshcd_negotiate_pwr_params(const struct ufs_host_params *host_params, 
}

EXPORT_SYMBOL_GPL(ufshcd_negotiate_pwr_params);



/**

 * ufshcd_parse_gear_limits - Parse DT-based gear and rate limits for UFS

 * @hba: Pointer to UFS host bus adapter instance

 * @host_params: Pointer to UFS host parameters structure to be updated

 *

 * This function reads optional device tree properties to apply

 * platform-specific constraints.

 *

 * "limit-hs-gear": Specifies the max HS gear.

 * "limit-gear-rate": Specifies the max High-Speed rate.

 */

void ufshcd_parse_gear_limits(struct ufs_hba *hba, struct ufs_host_params *host_params)

{

	struct device_node *np = hba->dev->of_node;

	u32 hs_gear;

	const char *hs_rate;



	if (!of_property_read_u32(np, "limit-hs-gear", &hs_gear)) {

		host_params->hs_tx_gear = hs_gear;

		host_params->hs_rx_gear = hs_gear;

	}



	if (!of_property_read_string(np, "limit-gear-rate", &hs_rate)) {

		if (!strcmp(hs_rate, "rate-a"))

			host_params->hs_rate = PA_HS_MODE_A;

		else if (!strcmp(hs_rate, "rate-b"))

			host_params->hs_rate = PA_HS_MODE_B;

		else

			dev_warn(hba->dev, "Invalid rate: %s\n", hs_rate);

	}

}

EXPORT_SYMBOL_GPL(ufshcd_parse_gear_limits);



void ufshcd_init_host_params(struct ufs_host_params *host_params)

{

	*host_params = (struct ufs_host_params){

drivers/ufs/host/ufshcd-pltfrm.h

+1 −0
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ int ufshcd_negotiate_pwr_params(const struct ufs_host_params *host_params, 
				const struct ufs_pa_layer_attr *dev_max,

				struct ufs_pa_layer_attr *agreed_pwr);

void ufshcd_init_host_params(struct ufs_host_params *host_params);

void ufshcd_parse_gear_limits(struct ufs_hba *hba, struct ufs_host_params *host_params);

int ufshcd_pltfrm_init(struct platform_device *pdev,

		       const struct ufs_hba_variant_ops *vops);

void ufshcd_pltfrm_remove(struct platform_device *pdev);