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Commit 6584ae39 authored by Brad Love's avatar Brad Love Committed by Greg Kroah-Hartman
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media: cx23885: only reset DMA on problematic CPUs 



commit 4bd46aa0353e022c2401a258e93b107880a66533 upstream.

It is reported that commit 95f408bb ("media: cx23885: Ryzen DMA
related RiSC engine stall fixes") caused regresssions with other CPUs.

Ensure that the quirk will be applied only for the CPUs that
are known to cause problems.

A module option is added for explicit control of the behaviour.

Fixes: 95f408bb ("media: cx23885: Ryzen DMA related RiSC engine stall fixes")

Signed-off-by: default avatarBrad Love <brad@nextdimension.cc>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b6f66e8b

drivers/media/pci/cx23885/cx23885-core.c

+53 −2
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <linux/moduleparam.h>

#include <linux/kmod.h>

#include <linux/kernel.h>

#include <linux/pci.h>

#include <linux/slab.h>

#include <linux/interrupt.h>

#include <linux/delay.h>
@@ -41,6 +42,18 @@ MODULE_AUTHOR("Steven Toth <stoth@linuxtv.org>"); 
MODULE_LICENSE("GPL");

MODULE_VERSION(CX23885_VERSION);



/*

 * Some platforms have been found to require periodic resetting of the DMA

 * engine. Ryzen and XEON platforms are known to be affected. The symptom

 * encountered is "mpeg risc op code error". Only Ryzen platforms employ

 * this workaround if the option equals 1. The workaround can be explicitly

 * disabled for all platforms by setting to 0, the workaround can be forced

 * on for any platform by setting to 2.

 */

static unsigned int dma_reset_workaround = 1;

module_param(dma_reset_workaround, int, 0644);

MODULE_PARM_DESC(dma_reset_workaround, "periodic RiSC dma engine reset; 0-force disable, 1-driver detect (default), 2-force enable");



static unsigned int debug;

module_param(debug, int, 0644);

MODULE_PARM_DESC(debug, "enable debug messages");
@@ -603,8 +616,13 @@ static void cx23885_risc_disasm(struct cx23885_tsport *port, 


static void cx23885_clear_bridge_error(struct cx23885_dev *dev)

{

	uint32_t reg1_val = cx_read(TC_REQ); /* read-only */

	uint32_t reg2_val = cx_read(TC_REQ_SET);

	uint32_t reg1_val, reg2_val;



	if (!dev->need_dma_reset)

		return;



	reg1_val = cx_read(TC_REQ); /* read-only */

	reg2_val = cx_read(TC_REQ_SET);



	if (reg1_val && reg2_val) {

		cx_write(TC_REQ, reg1_val);
@@ -2058,6 +2076,37 @@ void cx23885_gpio_enable(struct cx23885_dev *dev, u32 mask, int asoutput) 
	/* TODO: 23-19 */

}



static struct {

	int vendor, dev;

} const broken_dev_id[] = {

	/* According with

	 * https://openbenchmarking.org/system/1703021-RI-AMDZEN08075/Ryzen%207%201800X/lspci,

	 * 0x1451 is PCI ID for the IOMMU found on Ryzen

	 */

	{ PCI_VENDOR_ID_AMD, 0x1451 },

};



static bool cx23885_does_need_dma_reset(void)

{

	int i;

	struct pci_dev *pdev = NULL;



	if (dma_reset_workaround == 0)

		return false;

	else if (dma_reset_workaround == 2)

		return true;



	for (i = 0; i < ARRAY_SIZE(broken_dev_id); i++) {

		pdev = pci_get_device(broken_dev_id[i].vendor,

				      broken_dev_id[i].dev, NULL);

		if (pdev) {

			pci_dev_put(pdev);

			return true;

		}

	}

	return false;

}



static int cx23885_initdev(struct pci_dev *pci_dev,

			   const struct pci_device_id *pci_id)

{
@@ -2069,6 +2118,8 @@ static int cx23885_initdev(struct pci_dev *pci_dev, 
	if (NULL == dev)

		return -ENOMEM;



	dev->need_dma_reset = cx23885_does_need_dma_reset();



	err = v4l2_device_register(&pci_dev->dev, &dev->v4l2_dev);

	if (err < 0)

		goto fail_free;

drivers/media/pci/cx23885/cx23885.h

+2 −0
Original line number Diff line number Diff line
@@ -451,6 +451,8 @@ struct cx23885_dev { 
	/* Analog raw audio */

	struct cx23885_audio_dev   *audio_dev;



	/* Does the system require periodic DMA resets? */

	unsigned int		need_dma_reset:1;

};



static inline struct cx23885_dev *to_cx23885(struct v4l2_device *v4l2_dev)